If you shut off water to the house and open the interior taps the pipes are unlikely to burst. The water pipes in the exterior walls will get to roughly 1/2 the temperature difference between the interior and exterior. I.e. If its 0* outside and 60* inside the pipe temperature will be ~30*. Draining through the exterior hose bibs will probably get the water in the pipes to the lowest level. (Put an insulating cap on them also.)
If you have a programable thermostat you can raise the interior temperature of the house another 10* between 4:00 and 6:00 am.
It's best to cut off the power source to the water heater, whether gas or electric.
Anything you can do to add insulation to your windows will do wonders for your fuel bill. (For long term non-occupancy I'd cut something like foam board to fit the opening.)
If it gets cold enough for long enough even insulated pipes will freeze!