I use Base Clear Automotive paint on the hood. That works fine. A number of people have painted the upper hulls and not used Gelcoat. I did that to a 1996 XP I have. I would not even attempt to Re-GelCoat. I've had a lot of success restoring Gelcoat by sanding, compound, and Polish. Gotta remember these are old skis, the paint doesn't have to be perfect. If it looks good from 15' you are golden.
Concerning repainting the bottom of the hull, I purchased some hull paint (black) and plan to repaint the bottom of my 2000 RX.
On a side note; matching paint with the camera color match system is fantasy. It will get you close but the formulas have changed as well as the materials used. I don't even use it. I get the color strips and compare.
Good Luck!