F-250 intake manifold gasket leaking

1986 Ford F-250 HD 351HO V-8 4x4; 86,000mile(2nd time? - Registration was 86M); Auto Trans; bought for son's first truck 2 year's ago; did some local repairs, and drove non-stop 800 miles home in August heat, with working A/C and never over-heated, etc. Pretty solid. Then did radiator shop in fall, normal service, heat and A/C OK, best AF, new stat, etc. Truck then sat for a year as son could not get license due to insurance costs, but truck started and drove every month. A year ago, went to shop with dyno to check out before sinking money in. Good engine, compression, some oil leaks, and lots of other stuff to fix. Truck has been sitting outside at same shop for a year as we got time and money to do repairs. New carb, valve cover gaskets, rear main seal, A/T seals & kit, emergency brake system, rear brakes (drums, shoes, cylinders, lines)(front brakes 1/2 OK yet), cleaned wheels, tires, 4x4 & diff serviced and work, front end tie-rod, links, etc, new Optima battery, best parts for all repairs used.

Last 2 weeks I have asked the shop to triple check all and road test to make sure ready to go, so son can get license before winter, etc. A-OK they said. So I go there yesterday, and dropp my truck for LOF and Fall inspection and drive his down road. Upon first couple of stop signs, there is a bad scraping sound coming from the front brakes I think. Get to gas station and fill with premium ($54.00), and head down highway to a meeting of mine. Truck drives great! New tires perfect - may not need fancy new shocks - carb is smooth, low idle, perfect pedal response (hard to drive before), truck stops good for highway lights, except for front scraping sound. But after 5 miles/10 minutes, starting to smell bad burning smell like brake fluid or shoes or pads hung up I'm thinking. So I call shop and they say come back. On way back I see temp gauge going above the 1/2 point to 2/3-3/4 (never did before). At shop when they moved it into a bay, there were several small 50 cent sized leaks of something in the drive. 10 minutes later, mechanic came with one of the owners and said that it was coolant leaking from the intake manifold thatt was the sickly sweet burning smell, and that they would check to see if the manifold could be tightened, but that it would probably be a new intake manifold gasket, and it would be risky to drive it, and have coolant get in the engine, even if refilling the whole weekend. Finally my questions are:

1. Obviously it needs the new gasket, but -

a) how could this happen when it wasn't that way coming into the shop, and with all the tests, and work, and then the road tests the last 2 weeks, how does it just blow when I drive it for 15 minutes?

b) is it in any way related to the new carb or valve cover jobs - I'd think not, but I'll ask anyway.

c) what is the best quality gasket for this engine so I don't end up with some cheap local auto parts version - even if I have to order it and FedEx it in?

d) what is the best R&R procedure, and any special gasket sealers to use?

2. On the scraping sounds, we are waiting until Monday to get into that, but so far they're guessing it's corrosion or rust from sitting.

a) OK, maybe, but if they road tested it several times in the last 2 weeks, how could they not have heard anything - when I just drove it a block or two and heard it big-time at the first 2 stop signs?

b) Since the front brakes have been about 1/2 since we bought it, and the total rears cost a lot, I have planned new pads for the next round in a few months - just thinking that that will drag us into new stock or slotted rotors, cylinders, etc, and money is tight right now.

c) Any ideas of the front braking noise and what can be done economically to help - I could maybe do pads, but not $500 or more worth of new work right now.

Thank you in advance for your help with this today!