Do I have to run hack_init only once or every time
Only once, until you install 2.0b14. If you run it again it won't find the /empeg/bin/player string and will exit with a message similar to 'didn't find player string is /bin/init already hacked?' and won't do anything.

Interesting that the bug is so reproducible, and it only happens when you start gpsapp, go back to the player and return to gpsapp? Did you do anything in gpsapp besides waiting for a location update?

Does anyone else see this? I've just tried this about a million times and the player never even skips a beat, let alone switch to aux.