Mate, best place to look for this info is:
There’s an email address at the bottom of this page, they’ll be able to answer specific questions.
I think that you can only get a working visa for one year and as to whether you’d get hired on that is unknown. Check at the Aussie consulate in Vancouver on this though, they’ll have info on visa’s etc, this stuff might change from time to time.
Just my opinion but I reckon it’s easiest to come down here to do all your study and flying if you’re serious about it.
Sorry, I don’t know anything about instructing so I can’t answer those questions.
Anyway mate, good luck,