You can get some online tutorials for NX at
www.myigetit.com. They have tutorials for CAD, CAM, Assemblies and even Post Builder. I have been using NX for a long long time. You can still output a .cls file and continue to use the "old" postprocessors. All you need to do is click on the the Output .clsf icon.
Why don't you have access to GTAC?