A: Gel stains, as all wood stains, were formulated to go over raw wood which has an "open" surface and can absorb some of the stain. It is more difficult to obtain proper drying characteristics over a dense manufactured surface such as laminate. Fiberglass would pose the same problem, therefore, it is not advised to use on fiberglass.
A: In my opinion, (I'm not a professional, but an intermediate DIYer) I would say, yes. I would definitely try it. In this case, if it were me, I would take the time to scuff the entire surface and I would use a foam brush to apply. If the white has a smooth finish, it may wipe off if you try to rub it in. In that case, don't get discouraged, I would let it dry completely (as directed) and keep adding coats until you like it. Don't worry, a little gel stain goes a really long way. If you are unsure, try a scrap piece, inside a door or even a kick board.
A: Yes, absolutely! The coverage of this item is amazing. Of course it’ll take more than one coat, but the finished project is always rich & worth it!