RE: How do you stay warm?
In really cold weather I'll put one of those heater pads for back pain on over my bottom layer. The heat pad warms the kidneys, thus warming the blood and I'm roasty all day long. On extra windy days when the wind is whipping down the back of my collar I'll put on one of the neck pain heat pads.
I haven't had to use this the last few years though as it's been so warm in the winters.