This is just me saying, but I would not put them out without heat if it's going to b that cold. IIf u redece heat by 5 degrees each week and with babies u start at 95, they could handle 60 or 65 degrees. I'm very over protective tho. If u put them out I would put a heat lamp with them.
Yep. They will be fine. At 7 weeks old they are old enough to take a cold snap even. Don't worry. That's what their feathers are for. And no, they don't need any lamp/light. Unless you want to comfort their little "I'm scared" peeps.
remember they are wearing a down coat.....mine won't let me close the coop door at night now, and it is still getting to below freezing here in Colorado...they are 9 weeks old...fully feathered and loving it!