Re: Gel coat cleaning???
I start with car wash, then move to cleaners like greased lightning or the green cleaners/etc. If they don't work then it might be mold and shower cleaners work great on that like tilex. Last you can try naptha/mineral sprits/lighter fluid, all about the same thing wipe on and wipe off will not harm gel. Or you can go with an automotive polish it will not hurt the gel at all and you will give it a little shine while you take the stuff off. Wash before you polish you don't want to scratch it up. I used to buff boats with soft scrub all the time, it also works nice on boats. The bleach version is great on light color boats.
Wax is up to you, I still like turtle wax carnauba or nufinish for near any boat or car.