I don't know why Superman and Superboy are buff because they get there powers from the sun. I don't even know how they could get buff nothing on earth is heavy enough for them to workout with. But your art is still beautiful.
The cartoon is not a strict fallowing of the comics. Before the new 52 Superboy could fly he had super-strength, ice breath, heat vision, and tac telekanisis. Post new 52 is seems he can only only has tac telekanisis, heat vision and flight. The tac tele simulates super strength, and flight but no real super-strength, or flight.