Wow, That's a great coop! Very pretty. I live in New Hampshire and the winters get pretty cold here. The birds don't seem to mind the cold very much. I make sure they are protected from the wind blowing. One thing I noticed with chickens, is that they hate to step in the snow. If you want to let them stretch their legs in the winter, you may have to shovel out an area for them to walk in.
I use the deep litter method in my coop and run. However, I use chopped straw mulch, not shavings. I just stir it around once a day. It lasts a long time, and there is only the smell of straw when I open the coop door. I tried sand when I first started out with chickens, but found myself constantly scooping it out more than I cared for. It also raised a ton of dust as the chickens loved to dust bathe in it.