Just adding some experiences that I've had biking through several winters with my hard tail.
SALT: It really comes down to keeping the salt at bay. It's doable, but it takes work. The main thing to do in the winter is once a week; wipe down the chain (dry), apply your lube, wipe again, lube again, and wipe off the excess. Also, you'll want to use a few q-tips to get any gunk out of the two cogs of the rear derailleur as that will build up fast. This will keep the salt and grit from doing the most damage.
The main problem is that the stanchions need to remain intact of rust and pitting to move smoothly, and that the innards remain sealed off. Below freezing, the seals will contract and open up and become brittle. Salt will get into the fork and destroy the insides. Salt will also rust the stanchions and cause pitting that can facilitate debris to come into the the fork even in the warmer months if it gets severe.
Using some kind of covering (eg lizard skins stanchion boots) will protect from salt and grit corroding yours posts and from building up around the seals. You'll want to use suspension (fluoro) lube to keep it clean and smooth. For the winter you should check this every other weak.
The problem is grit. Salt will do more damage as an abrasive in this case than corrosion. The main thing here is as a mentioned above to keep this as clean as practical. The salty slush will wash away oil quickly. So even if don't have time to wipe is down, if it looks dry, lube it a bit. See rust? Lube it before it gets worse.
This is the most fun bit. Since the seals have shrunk and are stiff the salt can get into the bearings. If this is let to go on you'll end up like me with a seized freewheel hub. Best solution? Apply some (a lot of perhaps) grease (preferably the same as the bearings are packed with around the rubber seals. You'll wan to wipe it off and reapply fairly often to prevent salt from working it's way in there, but it is a lot better than rebuilding/replacing your hubs.
Almost an after thought... I have only really used disks in the winter so I may add that you'll want to "warm them up" before you need to stop. The main things that the brake pads clear any debris and water from the disk. I think it also helps the friction when it warms up as well, but I don't know that for a fact.
If you have v-brakes... I'd try to get discs if possible. The rims well get even dirtier than disks and I can see dirt not clearing out v-brake pads.