[tsubaki]

Welcome to the site.
bradford's got good points and advise!
I'm one of those people that will do the minimum until it is to the point to go all out.
Marine Tex is gonna be best for the gouge locations.
If the bottom paint has been installed correctly by coarse sanding or blasting the bottom of the boat, it may be a bear to remove for repainting.
Repainting with a different color will easier show the new scratches. There is probably nothing as tough as the original gelcoat, even Imron.
If you really want to change the appearance and the existing paint is passable/cleanable, think about stripes or designs on the sides.
Lets say you do freshen up the anti-fouling and repair the gouges. It probably can be done with it still on the trailer, just work the locations you can see first and pull the boat back a little (tied to a tree or vehicle). If you must remove a roller bracket or bunk for better access, do so.
I'm just sorry that way,

hows about some pictures???