RE: how do you stay warm
I ditto the boot covers. The biggest downfall for many people is their feet. My feet can't last more than a couple of hours in below 30 degree whether and I wear the right sock combinations and have used the foot heaters. But if I wear the right boots and socks and then slip on the boot covers with a couple of heater packs in each, I can stay out from sun up to sun down. Also, the right long underwear is crucial. The good stuff lets you wear lighter outerlayers critical to moving silently and drawing back.