is it possible to "convert" an FS2k2 plane to FS2k4? if so could someone explain it to me?
Asa general rule "yes" .. just copy it over to the FS9 folder.
Caveats:
FS2002 was still "backwards" compatible, so you could have models built with earlier modelling programs with some moving parts, etc.
FS2004 has limited backward compatibility. It will accept easily models built to the FS2002 specifications and eye candy but earlier models will have parts visibility/ animation problems.