Yes - somewhere, often in the luggage area, there are some air outlet vents which will allow the small air pressure built up by the speed of the car or the fan to exit. These often have some sort of device to prevent inward air flow.

Often cracking a window open slightly will increase the airflow through the car in all situations.

Most AC units have two modes; recycle the inside air or bring in air from the outside and cool it. Usually the Max-AC button will recycle the inside air. If you look at the AC controls closely you should be able to figure it out.

Sometimes - mine has two settings, one of which brings in fresh air, while the other recirculates the air already in the car (which gets it to temperature more quickly)

Timbo and Robert B are both right - even in recirculate some air (typically 10%) is fresh.

Hi yes of course it does it just means the air conditiong pump is not switched on.