Anything is possible. We could power the entire US if we put a large collection of panels in the desert. Surprised there aren't self cleaning panels yet (maybe there are) :).
Yes, but why? You've got all the maintenance headaches of wave power with none of the benefit.
It might be useful for above-ground water reservoirs. They sometimes float balls on their surface to reduce evaporation in hot environments (especially ones with a breeze). If you could do the same with large arrays of floating solar panels, you could reduce evaporation and get energy out of it at the same time.