I dress in layers also w/polypropelene underwear. I don't sleep on an air mattress in the winter(gases carry away heat faster than solids do). I usually sleep on a cot w/ a 2" dense foam pad on top of the cot.
Not true, All the "solid" mattresses do is trap air in them by one method or another...that's what foam is. Either way, if you've ever slept on the bare ground in the winter you'll realize that an air mattress is worth it's weight in gold due to the heat you lose to the ground. (by air mattress I mean thermarest, not queen size
)
Don't wear cotton anything.
Drink only what you need and piss as often as possible before going to bed--your body has to heat all of that extra liquid inside too--plus getting up to piss in the snow sucks.
If this is real winter camping, bring earplugs. It doesn't matter how nice your tent is, wind will ruin your night.
Don't wear cotton anything.
As has been said, dress in layers.
Down bags are great if you do a good job to keep them dry, if you suck at that...stay with synthetic fill.
Be very careful using any gas/fuel powered device in a tent, asphyxiation and 3rd degree burns are a real possibility.
Put your cold wet clothes under your air mattress/sleeping mat rather than in the bag with you. They'll still get dry but you won't get cold and wet.
Keep your water inside your jacket, otherwise it will be an ice cube instead.
There are plenty more, but you really didn't specify what kind of winter camping you were planning on doing. Do you mean winter mountaineering or sleeping in a sleeper cab at crawfords?