Well, I would suggest losing the backpack. Get some panniers. In the hotter months, it will make a whale of a difference on how much you sweat (your back gets real sweaty, right?) and in the ice it will lower you center of gravity and help make you stable. Also, it is just all around more comfortable. No heavy load on your shoulders/back.

As far as winter clothes, I would start with a decent wind breaker. Nothing fancy, just compact. Other than that, you will figure it out. Bike specific clothing works for some people, regular clothes works for others. I do like to wear a base wicking layer, but other than that, I wear what is economical for me. I always like to have a decent set of gloves.