You want vinylester resin as it is not porous when dry. Polyester resin is porous when dry. You are are water line Let the two layers of fiberglass dry and sand Lightly spray some gray paint in the sanded area if you think you have laid enough fiberglass look for any valleys. If no valleys, use lesser or lower grade sandpaper to get a smooth surfacing. Last sanding you should use wet and dry sandpaper.
I would suggest using Loc Tite two part epoxy to fill in the small holes and let dry for a day. Then used 400 grit wet sand paper for final smoothing. When done, call me as we need to discuss painting.
THE WATER BALLAST TANK LID IS. UNDERNEATH THAT WHITE OR CREAM COLORED FOAM. LEAVE THAT ALONE. KAPISH!
You may want to retab the floor to the hull at this point. Any questions, you have my contact information. Invest in a resin roller and acetone too