Couple of questions for the paint and body guys

[MTCK]

My 91 crew cab has the trademark GM peeling paint and has already been repainted once. The 'new' paint is coming off in nice big chunks along with the original paint right down to the bare metal. Some pics can be seen in my build thread.

1) Do I need to strip the whole truck down to bare metal before the next repaint? Or is there a way to strip the stuff that is about to flake (pressure washer, chemical, mechanical etc) and then go from there?

2) The hood and roof have been peeled long enough that there is some surface rust. What can I do to protect these areas and keep it from getting worse that won't have to be undone when it comes time for final paint?

3) What should I be looking for in a paint system for the permanent fix? Single stage or clear coat too? For color I'm going to use a GM grey from a later model application so it is easier to touch up when it gets scratched etc. truck is a driver and will be used, not a show piece. That being said I do intend to keep the truck for a very long time.

Thanks for any insight - I'm way out of my element on body work.