Seems like a good list to me.
On the thermos, I find a waterbag that I can put in my jacket pocket works well and a nalgene bottle that gets filled with hot water at night and tucks in the sleeping bag (with a wool sock over it) is a nice bonus especially when just getting in the bag. As it and the water bag stays with me in the sleeping bag it doesn't freeze. But then again you run the risk of leakage.
Speaking of leakage... can't understate how good a pee bottle is during the dead of winter nights. Selection of the bottle is important as you don't want to confuse your tea for your pee if you know what I mean. Also make sure it is sufficient volume - 700 mL is good enough for me but 500 mL doesn't have the capacity

Now to avoid the nalgene tea vs pee bottle I usually buy a pee bottle at the store and dispose of it after the trip. It's always an interesting experience in Shopper's Drug Mart, holding a bottle of consumer drink up and thinking 'Will my penga fit in this?'
Alright enough of that talk. For winter thermarest make sure you purchase the right repair kit. The standard repair tape won't stick during the cold and the seam-grip silicone won't set. Thermarest used to sell these hotpacks glue kits that you soften by placing them in boiling water, then smear the heated glue onto your patch. This will set in the winter.
Good stuff on the snowshoe boots and winterboots. I find that mucklucks are bulky and overkill for snowshoeing and you don't need the insulation value while actively snowshoeing but it helps to have a -100oC mucks when standing around camp. Vapor barrier socks are also really good addition both for your snowshoeing boots and mucks. It keeps your boots from getting all stiff due to freezing of accumulated water in them during the night. Bring you wet socks (inside the vapour barrier) with you in your sleeping bag and usually your own body heat drives off the moisture over the night (best with synthetic bags as the down will soak up that moisture and hold onto it getting heavier throughout the trip).
Folding snowshovel is very useful for clearing a tent pad in deeper snow and I find it works better than snowshowes, especially if you have to chip away at ice ridges formed from freeze/thaw events. It doesn't hurt to have one of these shovels to help dig your vehicle out after returning to your entry point either.
Larger pot for melting snow. It sounds like you tend to rely on home brought water which does save a lot of fuel if you keep the water in liquid form. However, I inevitably end up melting snow for a lot of my water needs. A large pot (3 or 4L) is useful for this because snow has such a low density it takes a lot of volume and several pot refills to get that 1L of liquid stuff. I also try to make sure the pot is robust enough to use on the fire as well as the stove since you inevitably have a fire going in winter and why not use that heat source for more than looking.
Wood processing - full size buck saw or a 22" trailblazer style (18" is a bit small for winter) and decent sized axe capable of splitting larger rounds. No less than a boy's axe but I prefer my Gransfor's American Felling Axe for winter camping. Wood prep is one of those activities you spend a lot of time doing.
Sleeping beleclava, separate from your day one is nice for the night. Anti-fog ski goggles can be nice but that is a luxury. On tent stakes, I often find that snow stakes work better (just cut a stick, tie in the center and bury it parallel to the tie; tamp down and let the snow set).
Hand brush for camp. Always nice to brush off snow from your clothing before entering the tent, and brushing loose snow from inside the tent if you have a tent floor or tarp.
Snot rag...in your pocket. It gets a lot of use in the winter.
Thats about all I can think of at the moment.