While learning to flat spin... SLOWLY move the ailerons. often you need less then 1/3 of full opposing direction. Excess aileron can snap you into an opposing directionspin, or snap you into a dive. You can't reverse the ailerons too slowly (except you can run out of altitude...)

When learning to recover... plan on 4 rotations of normal spin on getting out of the flat spin. (If you allow that much room... you should have plenty of time to recover) Remember... the normal spin loses altitude much faster than the flat spin.

With enough power you can climb in a flat spin. You won't ever see a full scale do it... but I have seen models do it.

If CG is back far enough for flat spin to work... and the engine dies... its going to hit the ground.