1) Artificial Inteligent ,its used for air traffic control, and planes flying in the air space.
2)there's has to be 5 things
A: the model folder;wich should have an Mdl file and a cfg file
B:texture file:at least one or many more folders having all the textures of the plane..
C:Sound folder :it has to have a list of many sounds of the plane include a sound.cfg file, some planes uses other sounds and will only appears a cfg file using "Alias=x"
D: Panel folder: It would have things as a bmp ,panel.cfg(very important BTW)and the files *.Gau ,wich are the gauges ..
E: Aircraft.cfg its a very important file
F: and an *. air file like "cesnna.air"
3)repaint is a diferent Paint of the plane,for example you can find many repaints of the default FSX model b737-800 (Not in the game) by downloading it ,you'll download the textures in a new folder to be place it in the 737 folder ,then you have to assing in the aircraft.cfg this new texture ,for example american airlines textures..Is not two planes with diferent desighns ,Its the same plane with a diferent Paint..
4) Panels its a standard and the old common way to see the intruments as if you were in a real plane ,all of the FSX model has it its just a 2d view of the intruments,and VC its and entire view of a cockpit with the instrument and everything
5)in theory all should work, but inside of every aicraft are litle softwares like the Gauges and many are not compatible with it ,you may be able to see the plane but sometimes Gauges used for FS2002 ,Used in FS2004 are incompatible in the FSX,
also some textures wont show too well in some aircraft (Including some freeware FS2004 Citation X, wich need to be remapped
..lol)
You don't need to apologize at all, I sugest you to read some of the read me files in all the add-on planes (the ones you download should have it) you can learn by reading them..
Cheers