Flip is when they have heart attacks. You know the have had one when you find them flipped on their back.
I bought 50 of the Ideal broilers to send to my Mom. Yes you can have them in an unheated shop. That's what Momma does. She puts in two heat lamps (don't trust the clamps--tie them firmly) so they don't pile up under one light. You can use a refrigerator box--cut it in half from top to bottom and join them on the long sides. That will make a great pen and probably last 3-4 weeks. You don't have to worry about them flying out. They only need a pen with sides 18 inches tall. We feed them turkey starter or game bird feed.