I thought about using fiberglass epoxy on them smaller holes especially the one in that curve of the seat track, thats gonna be a hard spot to cut out and shape back in. Thats why I saved it for last.
I'm just starting the paint process and know next to nothing, but I would probably epoxy primer first and then the fiberglass...
I hope others chime in on my comment to either confirm or deny because I really don't know for a fact and I'm talking about but I keep thinking of sealing the metal so if water got in between it and the fiberglass it wouldn't start rusting...