Madman91, I second the suggestion that you look for a slightly longer, safer route. It will make the ride much more pleasant and hence something you are willing to continue. Surprisingly if you add a mile to your route and you average 10mph (which is very easy to do) that extra mile will only add about 6 minutes to your ride. So going a greater distance is not always much of a burden if you can do it without adding to the stress of the ride.

As for parking outside I do it all the time. I have a new hybrid that I've added racks and fenders, etc. to make it a good commuter. As the owner of the LBS where I bought it observed, I've made it look like a European bike and therefore much less alluring to thieves. I use a u-lock, cable lock and a frame lock that locks the rear wheel in the frame. Fortunately, my bike sits out in plain view so I don't have to worry a great deal about people taking a lot of time to steal it. When there is a forecast of rain or snow I put a disposable plastic shower cap over the seat to keep it drier. I think good maintenance should take care of any bike problems brought on by winter weather.

Good luck