RE: TPMS sensor alert.
If you expect the temps to be that cold for a while, go ahead and bump tire pressures up a couple pounds. Remember that tire pressures drop one pound for every 10-12 degree drop in temperatures. Another thing to watch is adjusting tire pressures in a garage that is warmer than outside temperatures. I see this problem at work every day. It's 65-70 degrees in the shop and 25-30 degrees outside. That will make a difference of 3-4 psi after the car is pulled outside. Also remember to check the tire pressures before driving. As you drive, the tires will warm up and increase pressure by a few pounds.
Personally, I hate TPMS. I am still trying to figure out a way to mount all four TPMS sensors in a spare tire so I can run regular valve stems on the four road wheels and not set off the TPMS warning light. Mounting the sensors to a wheel is easy, but mounting them in a way that still allows mounting the tire to the rim without damaging the sensors is the trick!