KMD88

I was like you 8 years ago when I bought my 70 Torino.  I knew nothing and did not grow up around other guys who worked on their cars.  No one in my family worked on cars when growing up.  None of my current friends worked on cars.  Even with those disadvantages I learned how to restore my car.  I learned everything by obsessively stalking the forums and watching thousands of videos.  I did it on my own.  By myself.  
You said you want to learn by doing.  You are right.  That is the only way.  When most of these guys started working on cars they were just teenagers working on their car in the driveway and even at the curb.  You just have to start with something small.  Figure it out and build your knowledge little by little.  Unfortunately, it is very unlikely someone in a car club is going to take you under their wing and help you with your project.  They probably have their own project they need to work on.  I would just keep watching the videos and doing the research.  Good luck.

I put this on my Vette, and intend on installing one on the Stang too: 
I used a Rear View Safety RVS-776718-CT mirror and camera ($280). Its camera was used in the front (for parking curbs) with RVS-778 ($100) for the back, and has a license plate bracket so you don’t need to drill holes in the body.

I was thinking maybe choke hanging which means less air through carb hence flooding and gas smell. If you are smelling raw fuel tho then yes I would be looking for a leak some where.

Back in the early days, I had a problem with the stud that the cable attaches to was loose in the starter and caused an intermittent problem.

Yes, I kind of assumed you tried the easiest things first.
1 Good battery
2 Clean battery posts and cables.  .
3 Good solenoid.
4 Good starter wire cable.
5  Good ground from battery to engine.  
These are easy to check and verify they are working before replacing  the starter.  

Before you play with the starter, check the solenoid.  When the problem is occurring listen (or have someone listen) for the solenoid to 'click'.  If you are touching it you may even feel it operate.
Dirty connections are also a possibility
1 on the battery, 2 on the solenoid and 1 on the starter motor.   All easy tests before you pull out a starter.

I am wondering if the starter has bad.  A similar thing happened to me.  The brushes in the motor were not making good contact when they were hot, and so it would not start when it was hot.  It would start when the starter motor cooled off.  
If it happens again ( not starting when the engine is hot) have a bunch of water with you.  Dump a bunch of water on the starter to cool it off. Then see if it starts. You have to be careful not to get water on the exhaust or engine block, but just on the starter. 

Bad connection at the battery terminals, most likely. 

If it only happens when engine is hot, your starter might be getting heat soak.

I'd install a relay for the headlights. Takes the heat off the switch and let's the relay do the work. It also increased the brightness of my stock lights. If I can do it,  anyone can. I believe this is how I wired mine. 

While I was at it, I also did the horn which Mustangs have a history of fire issues with especially after market steering wheels. 

Just a thought. 

could be the headlight switch or the headlight dimmer switch on the floor . if it happens again try depressing the dimmer switch just a tiny bit. if nothing happens try dimming the lights for a few seconds a few times.
 
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Either way is fine.  When I'm not certain if or how much to pump the throttle I will start cranking first.

yup, that was about 18 years ago but I drove it to work everyday year round and I don't recall ever having a problem with it.

I would forget what the mechanic said and check the timing and carb yourself. A mechanic is rarely a tuner.

I’m having a similar issue with both my 82 and 70 with the Holley 600. Next time after it been sitting remove the air cleaner, hand throttle and see if the squirters are squirting. Once I engage the pump lever further, it’s begins to squirt. Fires right up after that.  I believe it’s the gas these days

Your accelerator pump diaphragm may be dried up or needs adjusting if there is free[play in it.

Prob needs some adjusting, both carbs are less than a year old. 

Your 600 CFM Holley likely has an electric choke.  They work good, but, one drawback of electric chokes is they cool and reset faster than the engine cools.  After sitting an hour or two the choke might be closed again, then plus some pumping of the throttle causes the engine to flood.  One other possibility is when sitting for an hour or two with a hot engine, the fuel in the carb bowls heats up, percolates and drips into the motor through the circuits inside the carb, thus, flooding the motor.  One of those thick heat insulating gaskets or a phenolic carb spacer will usually stop that from occurring.  The latter situation is more common when aluminum intakes are installed and the heat crossover passage is not blocked.  Another much less common cause of flooding with Holley carbs when the motor sits is leaking metering block gaskets in the carburetor.

Set your priorities. I did that 30 years ago, and still working on items.  Brakes and steering first.  Some of the prices and items seem way out of line.   Get it driving safely first, and then work on the smaller items.  Repair things as they break. 

If you are seriously considering having this shop do anything on your car, I strongly suggest they give you a separate price for every single item AND the exact brand and part number for each pat and the exact labor costs. The labor could be bulked together where several items in the same area are being changed at the same time like the front suspension. Then post that info and we can tell you for certain if you are getting hosed or not, but from what it looks like, you may very well be.
 

Make sure you don't buy cheap chinese UCA, I got the scott drake 4-rivet ones after one of my china crap UCAs locked up after 2 years and so far, they work.
If I would buy today, I might also consider dynacorn #3631JL UCAs

Here's my take - some of that may be reasonable and some of it definitely is not.  For instance, it's definitely not a good recommendation to put in performance suspension & handling for $5K.  That's NOT mandatory.  You can get new stock UCA's for lass than $50 per side (that's a lot cheaper than $350/side).
Don't put in 620lb springs up front unless you want it to ride like a covered wagon.  I think stock springs are 300 lb/in.  Don't lower it, but instead:   The top 3 upgrades for front suspension improvement are:
Redrill your shock towers to do the "Shelby/Arning drop" (if not already done) with new UCA's ($20 template + $100 for both UCA's) Put in a 1in" sway bar.  (best bang for the buck I think and makes the car safer to drive) $140 New KYB Gas Adjust shocks (Maybe $100 for both) After that, you'll need Tie rod bushings ($40ish), stock perches ($40), new spring seats ($10), some Tie-rod work
So that's like $400, and it will drive fine (not like a racecar, but you won't shatter your teeth going over the railroad tracks either)
On the rear, I would not buy new springs unless they can show you they are bent or ruined.  Just New KYB gas adjust shocks and see how it is ($100), maybe new leaf spring bushings if she's rattly.  Since there are traction bars, this will be more work.
So that's maybe $200 on the rear, and most all the big stuck on suspension for like $600-$700 in parts.  If you do this work yourself (only thing really dangerous in compressing front springs).  If you want to pay to have this done, $1500 is probably not outrageous, but I wouldn't buy new leafs. if they say they are "shot" make them show you how. 
Brakes are most important:
replace all the rubber brake lines, 3x maybe ~$50 each.  The following statement however - makes NO SENSE to me: "Found rear brakes contaminated with rear axle gear oil."  I have no idea how this could happen.  Sound like BS to me, and I would ask about it.  These systems are not connected, and I can't see how they could be thru parts failure, so I call BS.  Get a new drivers drum if you can't find someone to machine it.  New pads (cheap) and get new rear cylinders (cheap).  My brake backing plates are grooved some, but still work ok - weld and remachine is a fair bit of expensive work, and I'd try it without doing that.
They don't mention the brake distribution block or the proportioning valve.  The prop valve should be taken off and have a new seal kit put it - virtual certainty it needs that ($35 for parts).
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Engine:  That's an expensive radiator.  I bought a 3-row copper for about $350.  You can get a thermostat for $5,  you probably don't need a fuel pipe - I wouldn't do that.  If you flush out the fuel tank, there is no need to move the fuel filter ahead of the fuel pump (non stock).  New rubber connections ($10), New fuel pump $30, new filter $5.  That's all that's required.
If they can show you the leaks on the manifold you should fix it.  And you can look for this yourself, by simply wiping off the front and back and driving it around.  If it's leaking oil you should be able to see it.  personally, I don't need to remove the Ac compressor to work on the intake so - my opinion - not required.
Your oil pan probably is leaking.  Do you need to spend $1000 to fix it?  NO.  This is a hard job to get the old one off and put on a new one that doesn't leak, but honestly, you can keep the oil filled while you save some $'s to have it fixed later for cheaper than that.
Fix the motor mounts.  If they are original, they probably are cracked.  $320 seems like an ok price to do that.  Engine balancer MAY be needed.- if you can't get it to run.  But if it runs/timing is OK, I'd do this later.
For the love of God, do the all the AC/PS/alternator/fan belts yourself - any person driving a 69 oughta be able to do the belts.
No idea on the improvised trans inspection plate, but it's probably fine (it's a piece of sheet metal to keep crap out of the flex-plate starter engage area).  look at it yourself and see how bad it is.
Trans mount is good chance it is bad.  $125 seems reasonable
I'd note the rear axle seals as something to watch, and do them later.  That alone is like $300.
buy your own heater hoses. $340 is outrageous unless he is putting Stainless braid on them.
Elec:
I don't know what he means "seat plugs" but they are dang expensive.  Fix the electrical that's broken and nothing else.  he's only giving you an AC diagnosis, which means there is another $1500 of cost to get the AC going probably.  Can wait.  Two windows at 60mph is usually okay for a lot of the US.
Body:
If the roof drip rails are leaking, that can allow body rust which you don't want.  you are looking at a lot of cost that may affect the paint.  so this is expensive.  Depending on the quality level of your paint, this may or may not be worth it.  Just do whatever to avoid rust.
OMG - do NOT spend $600 on the damn clock - buy a wrist watch!  $35!!!  worst case - pull it yourself and mail it off to be fixed.
Dash: LED light kit and printed circuit panel is all you need.  your fuel gauge either works or doesn't.  If it doesn't, I would change the sender in the tank for $30, and not buy a new gauge (which is probably fine, but inaccurate - they all are BTW).
Steering wheel can probably wait at $1250!!! Good lord!. 
Fix the windows.  those mechanisms probably need an overhaul - they are cheap systems, and if not adjusted properly, can bind and be really frustrating.
UGH.  That's a lot of stuff.  I'm not a fan of having other dudes do my car work, and so I don't know about labor costs.  Anything over $100hr is questionable.  $80 may be reasonable.  My costs above are for parts, not labor (all of mine is free, so I on'y see parts costs).
This stuff is not that hard to fix yourself.  It just takes time.  If you have more $ than time - this shop may not be that bad, but there is some questionable stuff  in here - other stuff looks reasonable.  it's a mixed bag.  
Good luck.
 

Much of our old classics can be repaired with fairly basic tools like wrenches, sockets and screwdrivers. If you are mechanically inclined at all, you could get the manuals and do most of the work yourself. There are videos, books and lots of help on more than a few Mustang forums. Join a Mustang club and get to know the people who work on their cars.You would save lots of cash and have the satisfaction of doing it yourself, and probably doing it better than most shops. You could still pay to have those things done you don't feel comfortable doing. 10 grand at a shop doesn't go far on these beasts. It may seem daunting but many many people do their own suspension work. Its not rocket science. Look at your list- $475 for a clock? Come on, you could replace that, fix a rattle in the back seat, and adjust a window. I'll bet you could do almost all of that list, make friends and get lots of help here. Get your hands dirty!
If you must pay a shop for all these things then prioritize- above all else the car must be safe so do the brakes and steering first. The speedometer is fairly important but replacing the cable and perhaps the speedo is far less expensive than installing a Dakota Digital- although I must admit I lust after one myself.

Brakes and steering first here also...