I'm rambling so I will end this, but basically you want somthing for the hens that can be between 68 to 75 degrees in the winter. I also found a post on this site before I became a member about hanging cabbage inside there roost in the winter to give them something to do. And it's also good for them. But I'm very nervous about winter, since this will be my first with my tiny flock. Good luck and Go Ducks!
Please be careful keeping it so warm in the coop over winter. Chickens, even the less cold hardy ones, do develop more feathers and fluff to protect themselves from the cold. They do better overall in the cold than in the heat (I have hot, humid weather here during the summer and cold, sometimes into the negatives, during the winter - though only for short duration). Heating a coop to that warmth (68-75) during the winter can be dangerous as well as expensive, though there are definitely ways to do so.
The main thing is to get your ventilation where it will move the air up and out - especially during the colder temps in the winter. It's coops that aren't ventilated, where stagnant air gets too humid (from the birds' breathing and their waste), that you have the most danger of having frostbite on toes, wattles & combs. Their breath condenses directly on their own beaks and combs - causing the frostbite to occur if there isn't enough ventilation. I've dealt with frost bite when it wasn't all that cold (above freezing temps) - but my coop was too enclosed w/o good airflow - birds were miserable and the ones that were the most miserable started not wanting to coop up at night. Then they healed and fared better, even during two ice storms where they huddled against a trees w/ many branches protecting them, while I was still dealing with frostbite in the coop.
And to help to draw the birds out of the coop during the worst weather you can keep bagged materials around - leaves, grass clippings, hay, straw etc - and put that down over wet areas or snow. They will soon venture out to see what's doing on - some even during the windiest snow storms.
You can do the more open coops like the woods coop or some type of wire pen/hoop built into a hoop with quite a bit of ventilation. DLM and Deep litter will both help to keep down drafts and to add heat (via breaking compost down). And what may seem drafty to you, might not be to the chickens. You need to check it during times of bad weather at the same level the birds are...