Here is the set up that I have for my Buff Orpington Chicks. The aquarium is a 40 Breeder and offers great floor space for the chicks. Its pretty easy to take the chicks indoors and raise them until they feather out. I allow feed and water to be available to the chicks 24/7...if you were raising a Rock Cross for meat, then you'll want to take the feed away at night.
Chick starter is very high in nutrient content. I don't think that it would be harmful for the hen, but if you want to feed regular chicken feed to the hen and save the higher nutrient food for the chicks....If possible set up a fencing around the hen so that she doesn't wander off and take the chicks with her. You'll want a fencing material where the chicks can get through, but the hen can't. Set up the chick feeders outside the fence and set up the hen's feeder inside the fence, but elivated so the chicks don't get into it. Course you'll want to have a perimeter fence so that you don't loose the chicks.