I rode a couple of Toronto winters on 1" slicks, and while I wouldn't recommend it (and my distances were quite short), it is entirely possible. +1 to the not leaning in turns -- I had several falls when I turned too aggressively. I've never used studded tires before, but I would use them if I were in a wintry climate again. Even if the roads are mostly clear, black ice can be a killer.

In terms of clothing, you will come to develop your own system fairly quickly: I had clothing calibrated to 5 degree (celsius) steps in temperature below zero, and very rarely felt cold. Oh, and I wasn't wearing cycling-specific winter clothing. This worked for me down to temperatures (without windchill) of about -20C / -4F.