it was minus 20 a few years ago in pamps and believe me it was bitter, you should get a snood or even one of those masky things that covers all your face in those type of temparatures, the brandy and hot choc was a welcome break we had loads of those that year
I find just keeping on the move keeps you warm, its when your stopping and starting all the time that that you cool down and the bones start to ache.
But I would go for layers, not big chunky clothes. The best investment you can make is in a good pair of gloves, if your hands are warm it keeps your cheerful and its makes it easier to hold the beer.
Gogs, i agree with what you say about keeping moving. not always possible though, i.e. when on a lift (especially if it stops for a while) or if in a beginner's class (lots of standing around waiting for your turn etc). Defo get some quality gloves!
buy a snood they are great, you can also get those discs that when you snap them they heat up and you can put them in your gloves have a look on fat face they had them on there