I can help you a bit if you like.

Generally, I think you've been well advised. Oz is a tough nut to crack. I'm originally from the US and have been here quite a while. I'm lucky enough to work for THE major airline here and I can tell you it's a very good gig. Pay, work rules, etc, all are similar to what I think you'd get at the US majors. The catch is that it's hard to get on and there are loads of overqualified applicants. However, the good news is that, after a very long drought, Q is hiring in fairly big numbers. I think it's something like 20 a month for the last year or so and forecast to continue like that for the foreseeable future. Total number of pilots is just over 2,000.
Cost of living you seem to have a handle on. To reiterate, Sydney is insane. But, so is Manhattan, or London, or Paris... Like most countries, if you want a reasonable lifestyle, you'll need to get out of downtown. If you're prepared to drive, you can do well in any of the cities. I'm obviously biased, but where I think we're miles ahead is in quality of life. It really is a great place to live- and bring up kids if that's on the cards.
Feel free to send a PM if you want, or reply here for the masses to chime in on!!
Cheers, TDK