Just an FYI your rotors are much less likely to rust being left out in the freezing winter than they are if you left the car inside a warm garage all winter. If you do decide to spray WD40 on your rotors use brake cleaner on them before driving the car in the spring. If you're going to put your battery on a charger make sure it's a float charger. Do not use one of the cheap trickle chargers. It will likely cause more damage to your battery.