Nothing of your issues have anything to do with GSX.
GSX doesn't place your airplane, the FSX placement is controlled only by the scenery. Since GSX doesn't install any AFCAD file on its own, it means you already had this problem before, you only noticed it now, but it's not related in any way with GSX.
Of course, if your AFCAD is wrong or you have an AFCAD conflict, GSX will be *affected* by it, just like FSX, so the Followme car and other services, will not work correctly, because they are using the information from the wrong AFCAD, same as FSX.
The issue is surely caused by an AFCAD conflict, you should use the free FSX Airport Scanner program to search for AFCAD duplicates at a specific airport.
