Provided the frog is not outside, the heat lamp is probably a bad idea. I would stay away from the minnows too - those tend to be full of gut parasites that can get passed on to the frog. The frog is sensible enough to move to the water when needed. Other than that, I think you're doing alright. Leopard frogs can be rather nervous in captivity and can injure themselves when they crash into the glass, so watch out for that. Provided the frog is eating regularly for you, I think everything will be alright.