For our ventilation, my husband drilled several 2.5-inch holes along the top part of the walls, just the highest and lowest walls, and covered them with hard-wire cloth. This has seemed to help our humidity a lot, and we clean out their coop every day or every other day, depending on how cold it gets, and I think that also cuts out a lot of humidity. We also installed some reflective insulation on the roof (we have a metal roof), and I noticed our coop stays warmer/dryer. The coop has consistently reads 10 or so degrees above the outside temperature, and humidity varies between 40-60% depending on whether it is snowing. We also have 2 radiant heaters for extremely cold nights, just to prevent frostbite.
Two of my girls always, always, always end up nesting on the bedding floor by the end of the night, and they are our golden lace wyandottes, so I know they are NOT cold in there. I think some chickens just prefer the floor. We tried training them to stay on the roost, and they just always jump down by 3 AM. Nobody bullies them off the roost bar, they just jump down and cuddle in their corners.
I am not sure about the towels to stop a draft, and hopefully someone chimes in with suggestions.