Two completely different issues here:
- The positions not matching the airport, are most likely you not disabling GSX Jetway replacement files for a 3rd party airport, which you are supposed to do, as explained in the GSX Manual, Page 7
- The "Gate too small" message has several ways to be dealt with, either at the airport customization level ( the "Max Allowed Wingspan" option explained at Page 37 of the manual ), or globally, with the "Ignore Wingspan when parking" option in the GSX Settings, explained at Page 30.
