We have a wireless flood/freeze alarm that has a red light that goes in the window and flashes for the neighbors to see. Fortunately for us one who we are good friends with is in heating and a/c. One thing we did not consider is when going from a few weeks away on vacation to the entire winter the batteries don't last long enough. So I am thinking of upgrading to this one Amazon.com: Reliance Controls THP217 Automatic Phone-out Freeze Monitor: Home Improvement
It would be connected to a BPS (back up power supply) and the phone line on FiOS also has a BPS. They are short lived but I am sure someone would let us know if the power was off for very long.
We have forced air heat so no worry about plumbing for that but we do drain the pipes by simply shutting off the water and opening the lowest valve, and outside spigot and connecting a garden hose to the hot water tank drain and run it outside to drain. It isn't as good insurance as filling the pipes with anti freeze but in the event of a freeze the water would at least not continue to run. I understand that your hot water heat plumbing can be filled with glycol to prevent freezing.
Mail wise we have a UPS mail box in Florida and change our address to there and have mail forwarded. UPS gives you a street type address not a PO box number. They will also sign for packages and will put a note in your box if there is something for you that will not fit. They can hold, forward and most anything else you can pay for. The one we use is also right next to the grocery store so it isn't much of a problem to stop. If you are with Good Sam show your card and they may give you 15% off.