bv280

I just bought a boat, its a nice royal blue. Problem is it has a lot of gel repairs. Color match is pretty good, but you can see where they sanded a low spot around every repair. When you look down the side of the hull it is very wavy. We are planning to paint the boat a nice silver if I can't block sand it down to make is look straight. The questions I have are:

If i need filler, what should I use on gel coat?
What kind of primer, self etching?
Or am I better off block sanding and spraying new gel on?

Any input would be greatly appreciated.