Hello! What an exciting path you have chosen to raise chickens. We have had ours almost a year as well, but I'de like to believe that we have acquired a lot of information both before and after our purchase of those four Buff Orphingtons.
Your coop looks very nice...nicer than ours even. I guess that's the way things go when you are using an old coop that your grandfather built back in the 40's! Blessing indeed. Anyway, regarding heat and winter, we have heat lamps that we turn on when it gets down below freezing. Their combs and wattles get frost bitten easily, even if they are in a coop. If they have this problem and they are pinned up throughout the winter, I would first start checking for drafts. Ventilation is another big one, as is insulation if you live in bitter cold climates. We have none of the above besides a few heat lamps and our first flock did very well throughout winter. However, keep your coop clean! There is no such thing as over cleaning...especially if the don't go out much. There's nothing quite as heartbreaking as surviving the winter with your first flock, only to have one of your girls die of mite infestation. RIP PATRICIA. Of course, we are learning as we go, but I will say that if you decide to utilize heat lamps, make sure they are safely installed and you do not run them all the time. The sunlight produces a great amount of heat, even when temps are cold, and if your coop is set up right with bedding and insulation, drafts sealed and proper ventilation, it will be conducive to storing the heat from the daylight to suffice for the remainder of the night. Again, each flock is different. You will get to know a great deal your first year, as the seasons change from one to the next. So take your time, enjoy your birds, and listen to them. If you spend much time with them at all, you will find that they will show (tell) you what they need.
Regarding the free range...I think it is a lot healthier for them than staying in a pen day after day. As long as they have shelter and a place to seek refuge from the elements, they will not only do good, but thrive!
Also, supplements are always a good idea for birds in the winter months to compensate for the lack of nutrients in the winter months. Check with old farmers, farm supply stores, and watch your birds. They'll let you know what works, what they like, and rather noisily they will show you what you don't like.
Happy happy chicken-ing!
A happy flock (low stress) is a healthy flock