I live in USDA zone 4, and was wondering how I can minimally keep my chickens alive through the long cold winters, when just picking eggs all over the 100 acre farm at their coops.
There isn't much to do at all. Chickens are just fine in snow and at night pile on top each other for warmth. The primary issue with cold weather and chickens is crop freezing. So pick a cold-hearty breed such as wyandottes, which are known to be very resistant to that problem.
Obviously the chickens will want access to clean, dry nest boxes for laying eggs.
If you want additional protection for the coop, build a wind block. Just make sure the coop always has excellent ventilation.