Chickens can tolerate cold much better than heat, and except in extreme climates do not need an insulated coop. Coop should be draft free and have sufficient ventilation higher up just under the roof.
Corn is not the best thing for hens and probably not for ducks either. The majority of the hen's nutrition should come from layer feed with a side container of crushed oyster shell- they will take as needed.
You may want to post on the Duck Thread - as to their nutritional needs.