does this drive in require a radio/ stereo if you're sitting outside?

Correct. Your need a radio to hear the movies. We have a limited supply of rentals. They are $2 and we hold a license until returned.

Yea u need a radio for outside of the car but one can be rented for a dollar an hour Id in the concession stand

Yes i think it does but you can rent them from concession stand if you don't have one.