Well, not to point out the obvious, but you can wash it off outside, you just have to take it in to dry 
(assuming you have an outdoor water supply that works below freezing, we don't)
I hose my bike down at work, then take it into the warmest part of the underground parking to dry, sometimes bring it into the building too. Getting the salt off really will help. I know people like disc brakes for their braking power, but I'm not a fan. I find the maintenance much harder to keep up with in winter, while old-style v-brakes I can completely disassemble, clean, lube and put together again easily.
Other tips - lube often, and expect shifting etc to be a bit slow. There are lots of tips here on TE about clothing for cold-weather riding too.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett