OverEZ Chicken Waterer, 12 Gallon, No Spill, Outside/Inside Use, Automatic

How often should the water be changed for fresh water?

Could you set it outside the coop up against the chicken wire would the chickens be able to drink out of the nipples?

Where can I get the water heater that goes with this?

If using a deicer (purchased separately) to keep the water from freezing, will that also keep the external wet nipples from freezing?