Most Aussie airlines require a Senior First Aid Certificate and a Responsible Service of Alcohol Certificate. Bothe are quite easy to obtain. As for previous flying experience, just put in on your resume. You can be guaranteed, they WILL do a reference check anyway.
If your
PR is due fairly soon, I would suggest you start applying now. Get your name on the lists, it might be another 6-12 months before there is anymore movement.
I am about to do the exact same as you, but in London... How funny!
Good luck!