Sounds like you've got the cold figured out very well. Being from the Sioux Fall area myself, I know exactly what kind of the winter you deal with! As far as what they're eating, I say if it ain't broke, don't fix it! So they're getting more corn than some say they should have - seems like they're doing fine so why worry? If you are planning supplemental lighting, just set the timer so it comes on way before dawn. Some say to have it come on before sunset and stay on til 8 or so, then on again before the sun comes up. But that plunges them into unexpected darkness at night instead of gradually dimming light, and they can get caught unable to get to the roost because they can't see.We live in Iowa and have some seriously cold, wet, windy nights. This is our fourth winter with chickens and have learned really to just let them adjust. I get the heaters out for the waters and make sure to close up the shed at night for them but that's it. I'd do more but we have nice big cold hardy girls that's (besides one roosters comb getting some frost bite) have never had any problems. I'm surprise to see folks who get only down to 30s and 20s doing so much to lock them up tight. I really think just acclimation and dryness is key. One thing I am wondering is what to do with winter feed. My girls free range on the farm and do go get stock piles of corn from the steers pen but I give them all you can eat straight layers feed. I know people warn about over corn eating but there's not much I can do about keeping them out of the lots and plus they enjoy being free birds everyday on our 10 acre farm. I'm going to try supplemental lighting this year for more eggs and worried that I may need to give them some more colories in there coop (especially for those really terrible nights that I can't get back there to open the coop until afternoon)