Bill (Ace-Garageguy) is definitely the man when it comes to fiberglass. Any advice or instruction you get from him you can take to the bank. I'm not sure that pics would do you much good. I can tell you that 3/4 oz. cloth is pretty thin, about like silk. That may be the lightest, tho it seems like I saw some 1/2 oz. somewhere. 8 oz. cloth (that I have used for canoe repair) is about the thickness of denim. The lightweight cloth is available from places that sell R/C aircraft building supplies. The heavier weights might be easier to find (and cheaper) at auto body or marine suppliers. I have found that one layer of 3/4 oz. cloth works fine for reinforcing splices in plastic.
Just based on what I have owned, I would say Ford. I've had a bunch of different cars, and I bought each one because it fitted a particular need and/or it was the best deal at the time. I've had seven Fords over the years, although two were Mazdas in disguise (Probes). Two F-150s, an F-350 dumper, and currently a Focus and an F-250. I've had a Dodge, a Toyota, a Subaru, a Buick, and an International Scout. All were excellent for what I wanted them for. I did not follow my parents, who were Dodge/Plymouth all the way, except for one Vega. I don't really think Fords are better than anything else, it just seems like when I go car shopping, I look at everything, and the best bang for the buck ends up being a Ford.
I've had good luck with Testors "Gloss Clear Lacquer" (in bottles). It works fine over their enamels. It's pricey, but if you do a good job sanding the color coat, it doesn't take much clear to get a nice shine. I haven't seen any sign of yellowing so far.
If your molds are made of RTV silicone rubber, you may not need mold release when casting. I've cast a bunch of small parts, and they come out of the mold easily without mold release. I've never done a body, mold release might be necessary for those. It's very important to use mold release when you pour the second part of a two part mold, as RTV sticks to itself really well. I've used both Smooth On and Alumilite mold release. Both work fine. Smooth-Cast 300 is easy to use and works well.
Those Sally's sticks look interesting and I think I will give them a try. I'm guessing they are soft and flexible. If you need something rigid, I've had good luck attaching regular sandpaper to various shapes and sizes of wood sticks, using carpet tape or spray adhesive. I've also used sticky back sandpaper, but I've only found it in limited (relatively coarse) grits.