Remember sweat can kill in the winter. Layer your clothing and if you feel that you are starting to sweat peel some layers off. Once your clothes and you get damp it can be real hard to dry out in winter. If you are wearing boots with removeable liners, it can be a good idea to have two sets of liners so you can have one dry out while you are wearing the other.
I personally cannot stand mummy bags, so for me I need the old fashioned rectangular bag. I like the fact that I can store the next days clothes in the foot of the bag so they are warm when I but them on. This does come at a price, the bag is heavier and not so compact and I have to wear something on my head. I wear what my kids call my "dork hat" it is a winter liner for a hard hat and covers my ears and keeps my head warm at night.

I would also suggest the first couple of times you go out, you don't go to far off the beaten track just incase you need to bug out if something doesn't go as planned