hey buddy im not a painter....as for the rash, you can prep it by sanding it down, bondo-it etc.
if its not cracked, its better, but if it is, plastic weld it, then melt the underside of the panel.
if you need help, id be willing to help, no cost just materials...i dont think paint shops will prep panels...if its only in one spot, fix it and decal over it.