I'm Canadian, I've worked in Canada, mostly Central Canada, but I now live and work in Southern California.
What an employer wants to see depends on the employer. The BFIs (Nortel, ...) have very elaborate interviewing and hiring processes, structured interview, background checks, etc. These processes are not geared towards finding the best candidate. They are there to ensure the employer does not get sued.
While smaller employers used whatever process they feel comfortable with. Which could be as little as the initial interview or requesting that you take a programming test. I suggest that you be ready for whatever they could through at you.
Speaking from experience of moving from one country to another, the change in culture is, or was for us more difficult to adapt to. While we had an excellent credit rating in Canada, we unknown to the major credit agencies and as such getting loans for cars or a house was very difficult. We had to purchase our car using cash from the proceeds from the sale of our home. Given that we moved here ~ten years ago and the Canadian dollar was not where it is today, we lost a significant chunk of money due to exchange rates.
Health care. Luckily for you, Canada has universal health care so you won't need to worry on that front. While hear in the U.S. health care is provided by the employer, if and only he feels like offering it. Having come from a country where health care is universal, being so dependent on your employer for health care makes you think twice about changing jobs.
Immigration laws and how they impact your employment is another issue. Given that I'm from Canada I'm not knowledgeable on Canadian immigration rules, but here is the U.S., once you've started the 'Green Card' process with one employer, it is difficult to impossible to transfer that petition to another employer. Our petition took five plus year to complete. And in those five years, my spouse could not work since she was on a dependents visa and I had to endure a very abusive boss. Something I would not have endured if we were back in Canada.
Education. Does the education system in the target country meet your cultural expectations? Here in the U.S. there are a many hot button issue. Namely, Evolution Theory, prayers in school and sex education, to name a few. If you have kids then you may want to find out what they are teaching in the Vancouver schools systems.
Don't under estimate the time and distance traveling between Vancouver and Sydney. I've done the L.A. to Sydney flight and it takes ~14 hours, plus a crossing of the international date line. Which means you'll loose a day, but you get it back on the return trip. Traveling that distance with small children could be difficult. Also, the cost of the trip can only increase with the cost of crude oil. Seeing family and friends will be less frequent since you really need to take two weeks off when traveling such distances.
Climate. Never thought I would miss winter! Southern California has the Fire, mudslide, and earthquake seasons! Vancouver winters are mild but wet.
Lastly, small creature comforts. Things that you enjoy at home that won't be available at your new place. Doughnuts! Too quote Homer Simpson. Krispy Kremes are no Tim Hortons. Favourite television programs, This Hour has Twenty-Two Minutes, Royal Canadian Airfarce, Saturday Night at The Movies, etc. Watching the Olympics from a different countries perspective! The only time we see Canadian athletes is when there are Americans participating in the event. Also, which of you electronic gadget will you need to replace? TV broadcast signals use NTSC encoding, in North America. Soon to go digital. As such you TV may be useless. Same could be true for any DVD or VCR. Electrical systems. We use 120/240 (110/220) volts. Got adapters?
Thing to think about.