I'm running the latest AAU1 Beta and the latest PMDG update:
- GSX will automatically connect the jetway. Or, more precisely, will try to connect the jetway before starting Boarding, because if the jetway doesn't connect for any reason, it will do a simulated "fast" boarding, with no passengers, but it will still do something.
Note that, with the PMDG, before any GSX service can start, GSX will first need to operate on the PMDG FMC to send a command to all PMDG vehicles to go away, and this will take about 30 seconds so, you might be easily mislead Boarding is not starting even if you called it, because it's waiting for all PMDG vehicles to go away.
That's why we suggest to create a custom State from the PMDG FMC, with with no vehicles, to be used for GSX ( or perhaps just the GPU ), so you won't have to wait every time, especially in case there's a jetway, since the PMDG always create its own front Staircase, even if the parking spot has a jetway.
- No problems with Pushback or Parking Brake detection I can see.