I can help with your second two questions.

Your wardrobe should at least have a few items for all weather conditions. Three weeks ago it was -30 here. One weekend last spring it was 98 and incredibly humid. Throughout the year it can, and will, range like that. For winter clothing, be discerning. There are stores like LL Bean and Columbia that will have good products and stores that cater to outdoors people like Cabela's or REI will also have good options. Don't cheap out on your big, heavy winter coat. It might not be the most stylish but you'll want something that will keep you warm in the winter and the truly good ones can cost a bit.

There is a bus system in the city, and it's free, but it's not the most all-encompassing route system. I would highly highly recommend a car.