Re: Bottom paint
Rent a needle gun [ use eye protection. ] get rid of the rust. Paint with Ospho. Two coats of zinc rich epoxy primer. Fair then two more coats. Do it on a warm dry day and get the first coat of primer on ASAP.
But using a wire brush, Ospho followed by some Home Depot spray galvanizing fair then a coat of anything will do as well. Just keep the paint handy because you will need to keep touching it up.
Not sure what is best for the hull. Definitely rub it down smooth and definitely apply a coat of primer after that ? Not sure. When I had a trailer sailor I applyed VC 17m and it was still looking good when I sold it 2 1/2 years later. But it is not cheap.