Cessna Capt,
The statistics for some of that is on the Qantas website... roughly, under 10% of those who apply make it through the selection. There is no aim to prevent cadets from reaching the job - its based solely on your performance (unless recruiting stops). Generally about 10% have missed out, but it varies from year to year.
Prospects to be employed elsewhere are the same as everyone else in GA looking for a job!
Lancer