The way I remember it is that you never want your plane on without the radio being on. So, yes - radio on, plane on....plane off, radio off. As far as the humming, I'm guessing that the servos are trying to move the control surfaces and the throttle arm farther than they can. If they don't hum if you disconnect the servo arm from the servo then there's a good chance that that is the problem. What kind of a radio do you have? If you have a computer radio, you can change the endpoints so the control surfaces don't move as far. Otherwise, you could just move the pushrods in closer on the servo arm or out farther on the surface control horn.