You can't, but if you stay away from the runway part, cops won't chase you.
I did drive Luis into the airport in a cop car and did not get any problems, but I don't know whether that was just a fluke.
by passing all the missions without cheating
All you have to do press triangle.
Go to the airport in Shoreside Vale. When you are entering the airport on the entrance road there will be a parking lot to your right - or to your left if you're leaving - and you need to go in there. There are always a few cars in there and there is always a Cheetah but I'm warning you that the doors may be locked in it. That's the only way I know to get a Cheetah without stealing one that's driving off of the street.
Yes, you can rent a car at an airport without flying.
Stories Without Words was created in 1987.
Yes, you can park at the airport without flying by using long-term parking services offered by the airport.
Yes, you can shop at the airport without flying by visiting the public areas of the airport where shops and restaurants are located.
You could fly right into the state if you wanted to for example Philadelphia International Airport (PHI) or Pittsburgh International Airport (PIT). If you only want to get close without entering the state you could consider Newark Liberty International Airport (EWR).
No, you cannot leave Heathrow Airport during a layover without a visa.
You are scared because if you enter water and you can not swim, you could drown. Real people can not become mermaids, that is just for stories.
you can't