First, our temps are quite similar to yours, right now at least, and mine are in the coop with a heat lamp only at night -- and they are ONE week old. They were grouping well away from the heat in early morning when it was still cool out there. Chickens are good about moving toward or away from a heat lamp if they have the space. They'll be fine in the coop with heat, and won't need the heat much longer, if they do now.
Lots of people lock chickens in a coop when first put there so they will learn where to go at night, for 2 or 3 days, or for a week, but that's when they are old enough not to need heat. I think with the heat in there, they will be more likely to go in on their own. I'd give them the freedom and just check on them after dark, and hope they go in on their own.
And I agree, they might turn out to be hens yet.
Good luck!