1: In order to be a pilot you must have a
score of 50.
The Pilot license can be bought for 50,000 dollars at the Store on the map which is a big S on your map on the server. After you have bought a Pilot license you will be able to fly any helicopter or plane you wish but the police helicopter. You can only fly it when you are a cop.
2: 1 rule when in the air is not to run into any other pilots or into anyone on the ground. Your 2nd rule will be no hacks or anything involving them meaning, Airbrakes, Speedhacks, or teleporting hacks, and etc. There isn't to much too say about the pilot it can be very simple or very complicated It depends on how you fly and how much you know
3: If you press E and Q you will use the back wing to turn side to side Q is left and E is right. And if you hold W you will fly faster and fly upward more and S will stop/slow you down for you too land or stop after you land. The A and D key will turn roll the plane if you hold them so to make a great or good turn. To make a good left turn press Q and hold A key and will make a left turn and if you press E and hold D you will make a good sharp right turn.
To enter the plane you can press F or ENTER. Best way to take off is to not to hold W and use Q and E to steer that plane on the ground and Make your way to the runway. As long as you don't Crash or run into anyone in the air or ground you should fly good and have no worries on land or air.
4: Once you do get your pilots license go up to a helicopter or plane and enter it once you do press T and type /work or press 2 and select 'work' to start a mission. The helicopter missions In the helicopter you could fly to bayside and turn around and fly to the oil plateform beside los santos. You could fly across the whole map or a short fly from Las Ventrues to Bayside You have a wide range of missions and helicopters So you would have a wide range of varieties.
5: The plane is just like the Helicopter just enter it and press 2 or type /work once you start a mission your missions will have you fly from Las ventrues airport to either Las Santos or San Fierro you will fly between these 3 airports and sometimes the abandon airport the plane missions are easy and can make good money doing these 2 aircraft's
Disobeying the rules can result in your license being taken with no refund. Just fly like you would in real life (if you have a flying license 
) and everything will be just fine.