no myth-busters did a review on it and you use more fuel with windows down then you do using the AC. AC uses the same amount of gas as running with the windows up and ac off
At speeds below about 30mph it is better on fuel mileage to drive with the windows down. Above 30, the drag from the open windows makews it more economical to run the ac and roll up the windows.
No problem at all, you can use the small fan.
no
No. While in air conditioning mode, the air will assist in the dehumidification.
that's a big negative
In short answer, yes. There are many things that will affect the temperature produced by an air conditioning unit, to be honest.
It depends on how cold you want the area that your using the air conditioner on.
One cause of a cars air conditioning to brake is the temperature of the air conditioner. Using to much cold air at a certain amount of time can damage your air conditioner.
NO
buying a car with a low gas mileage rating
Sunlight may affect the environment if you spend more money suntan lotion, (factories may have to make more) affecting the environment. Although without you even knowing you my be affecting the environment because you may have been using you air conditioning (more air conditioning more petrol/diesel ect.).
Driving the AC compressor puts additional load on the motor and reduces gas mileage.
You can only get gas heating and air conditioning. The gas heating and air conditioning is less because it uses less gas then how much water you would be using. The electricity for the heater and AC can be fairly cheep.