Some common causes of pealing paint are paint that has gone bad from freezing or being old before it was sprayed.But the most common cause is poor prep work prior to repainting.The old paint needs to have ALL origional claer coat sanded off and there can be no oil.smoke residue on the body or dust left from sanding.New paint will peel off eventually if the old paint wasn't properly sanded and cleaned.
As far as faded paint goes.If the paint is faded badly enough that the hand applied pollishes available won't work.Then I would say a detailing shop should be you'r next stop.When working with a power buffer and buffing compounds,it's quite easy to buff right down to bare metal on the bodies edges and curves unless you'r experienced with using a buffer.But if you really want to try for yourself.Try finding a cheap beater to practice on first.