Rolling suitcases tend to be best. One weighing 4 kg. on its own is a bit heavy but not outrageous.
Assuming you are flying to your destination, pack 5 complete sets of clothes in the suitcase, 1 complete set of clothes in your carry-on, and of course you will be wearing 1 set. That gives you a week of clothing, which is plenty if you choose items that mix & match.
The keys to staying warm in a snowy place are a knit hat, a good jacket, really good gloves, solid shoes (best lined with something like Gore-Tex) and thermals (at least thermal bottoms). Wearing poly-pro thermals under your clothes can be the difference between being warm and being miserable.