1. when you use epoxy primer, it is harder to sand and drying temps can effect it. If your using NAPA which is Martin brand paint ask for a data sheet. This gives you what you need to use with the paint your using. Fiberglass can use the same paint, but you need to seal it with the primer.
chips in fiberglass, you can use spot filler. BUT make sure you clean that hole are chip well, remember spot filler is just that to fill small spots or thin fills.