We leave them in. Momma keeps them in the nest for a day or two then they stick close/under her when they start moving around more. We offer pallets & things for chickens to get away from each other, often mamma keeps them in a secluded/hidden area. A lot depends on your set-up and birds per sq ft. You could also put busy foods in the coop, too, like squash or a sunflower seed head also to keep them distracted.

Yes they'll kill the chicks if the opportunity arises.
Brendasue