You might consider putting Vaseline on your chicken's combs and wattles to help keep them from getting frost bite. I have a heat light in my run. I have also put up plastic sheeting on the side of the run that always gets the most wind. You can buy an aquarium heater for your water if you have electricity that runs to your water supply. I don't think it is worth it as it doesn't freeze all that much to merit that. Try to keep the flooring dry as wet feet can lead to frozen toes and they could lose toes that way. My roosts are high and protected from the wind and wet. I don't overworry about our southern winters, we don't have the cold as bad as most of the country. A lot of the warnings you read about are for places that stay 'frozen' most of the winter. A few nights of freeze will be uncomfortable, but it shouldn't kill your chickens. Just make sure they have fresh water. That will be your biggest worry. Chickens in the south handle cold weather much better than they do our southern summers!