The amount of coats of the epoxy is up to the builder and the type of finish he wants on his boat. Personally I like to do three after the glass is wetted in and cured.
I have never epoxied over any paint and the accent strips on my boats are added after all of the epoxy work is done. So I can't offer any advise about epoxying over the latex paint , with some luck someone else may be able to offer some suggestions about that.