Well, for a first restore, you sure didn't take on an easy one. Good luck with the project and keep posting progress and we'll help you along.
As far as Bondo, you can really use any kind. I just use the basic 3M Bondo automotive body filler. If you want something stronger, I believe they make one with fiberglass in it.
The use of vinyl depends on the type of cab and how much work someone is willing to put into it. Most cabs didn't use vinyl and that is why paint is a good option. Using vinyl requires you do do all the same prep work as painting, including (in most cases) painting the cab and then putting the vinyl on top. Many people don't want to spend the extra time and expense using the vinyl. Check out
This Old Game if you need some vinyl as they have a good selection of colors.