Set thermostat low(55) but if power loss you will need to have the water shut off at the main and drain the pipes including the toilets. When you get back just turn on the water and fill everything up.

To drain the toilet flush until there is no more water after you shut off the main.

The big problem is if you have power loss and you have steam/hot water heat you can blow your heater. We have antifreeze added to ours for this reason as we are rural and have lost electricity and therefore heat and almost lost our heater.