my opinion: if the coop is safe and can be heated if need be (heat lamp or other source) you could actually use a coop as a brooder if the chicks are safe from the elements or older chicks or chickens, i would keep them shut in the coop when i'm not out there with them.
same basics apply, food water heat and security.
be careful of the bedding (litter) you use. no Cedar.
My chicks are outside in the coop. Of course I'm in South Texas and we have more warm weather than cold. With you being in Nebraska, you probably be best to wait until they are fully feathered which is around 5-8 weeks old. I don't have a light for my coop, they have the nest boxes to go inside to get out of the elements and lots of hay and each other to keep warm. It is breezy here today, but just cool.
1. Needs to be fully feathered
2. If bantam, needs to be big enough it cant get through the chicken wire.
3. Needs to be enough of them to create their own flock so the larger chickens wont kill them.
This usually means I take them out of the brooder, between 1-2 months. If I only have one or 2 birds , then I wont integrate them into the flock until they are big enough to stand the pecking order challenges.