My son flies full size turboprops. On the one with metal props, there is no restriction on reverse thrust, in fact they often use it to back into and out of parking spots on crowded ramps. The one with carbon fibre props has all kinds of restrictions on the use of reverse thrust, but generally, they can not use it below 60 knots. The heat affects both the props and the cabin windows. Those engines run at very similar temps as our little ones.

Metal props on model airplanes are not allowed here, and I would guess in many other countries as well..............