I've just been through the training process in Townsville and I am now a stage 4 after starting on the 3rd October 2011.
Pay stage 1-3
5 weeks in class doing standards and safe working which is stage 1.
5 weeks out on track observing safe working practice (we actually only did 3 weeks so we could be out of school by Christmas) stage 2.
4 weeks in class doing diesels and air, ATP and simulator which is stage 3.
Pay stage 4
3-4 months (so my tutor informs me) as a stage 4.
Other depots may do things differently. We didn't do distributed power as it's not required.
They put 15 on initially, 1 went to Mackay and one was sacked leaving 2-3 tutors spare.
As for OT you only get OT when you work your SLP or BLP (single or block leisure period) which we were not allowed to do until stage 4.
Hope that helps.