Educate me on paint

[3 Squids]

Going to pick up my new toy this weekend. It would appear that someone painted the boat with out proper prep. I'm thinking maybe it wasn't primed. The guy I had check the boat out for me said the hull is in beautiful shape, no blemishes or anything. I'm thinking I may repaint the hull sides. I've been looking at the Awlcraft 2000 topside paint.

I'm thinking I'd carefully sand it back to the gel coat, prime and repaint. My thought is what to do at the waterline. I'm afraid if I just tape at the line, sand, prime and paint it will give me problems at the waterline. Any input? Here's what is happening now.