I was raised in Michigan, and one thing I don't miss is winter. What a mess. Anyway, what you want to do is get a good sealant on there. Something like Rejex or Collinite should do the trick nicely. Get at least two layers on there.
As for the washing, you're kind of stuck in a bad situation. On the one hand, a touch carwash will ruin your paint, on the other, and a touch less will likely strip all your wax and sealant off because the detergents they use are pretty intense. Between the two, touch less would definitely be preferred.
If I lived there, here's what I would do (because I'm insane). I'd go down to a pay and spray wash and use the wand to rinse the car very well, using only water. Knock off as much of the salt and junk as you can. Then, I'd go into my garage, and use a rinseless wash like Optimum No Rinse (pm me if you need more info on how to use) . That product will safely clean the car without the need to get out hoses or anything, as long as the car is only lightly dirty. Definitely try to do this on a day when the roads are relatively clear so you don't gunk the car up too bad on the way home. Of course, this depends on your cold tolerance and level of mental instability, as washing your car in 30 degree weather is pretty crazy.
*In life, there are no nandroids*