I've never walked a 1/2 marathon Todd, but I would guess it's similar to running. You should be tapering with just a week to go. I am only running about half or less of my peak mileage this week and maybe a third next week. Rest is most important right before the race.
As far as the holidays and weather, its tough. I hate treadmills, so I try and run outside regardless. Just wear more layers of clothing.
Good luck next weekend. I am hoping for temps in the 50s and 60s. It can warmup immediately after I finish running.