First off, refinancing in Dubai for two homes in Oz would be an incredible hassle for you as well as the fact that it's a ripoff here. I recently inquired about a mortgage for a villa and I was quoted 8.5% with the usual criminal fees up front. After much bitter complaining on my part, they came down to 7.7% and cut the fees in half, but I still found that to be high. Just letting you know that I don't think that idea will come to fruition for you........ (if i read your post correctly.)
The starting wage for an F/O is about 23,000 dirhams. I think that equates to a little under 6000 OZ but do the math yourself. Accomodation is free though if you are in company accomodations. Somewhere around 110,000dhs accomodation allowance which will not come close to what you would get in company accomodations.
Don't take the furnished option. Do it yourself. Although more of a headache in the beginning, you will regret having EK furniture and appliances until the day you go out and buy some yourself. It was the biggest mistake I made when I came here, but I just didn't want the hassle of kitting out my place during my training course.
A half decent 4X4 roughly 120,000dhs, I'm sure someone can correct me on that one if i'm way off there. You get a 50,000dhs interest free loan for a vehicle which is deducted over a period of about 5 years from your pay. It comes to a little under 1000dhs a month.
You will save nothing if you have a wife and kids for the first few years. Especially considering you are planning on all that travel for the family. I would estimate that the average family pilot doesn't save much at all for the first 2 to 3 years. Naturally think look a lot rosier after upgrade but that could be anywhere from 3 to ???? years after joining.
Ability to utilize staff travel depends on loads, and thus dependent on your desired destinations. OZ trips are quite full. Perth and Brisbane are the 777 and Melbourne and Sydney are the A345. Staff travel is not that accomodating but the system in place for 'bookings' is quite good in my opinion.
I think you are dreaming if you wish to get to Perth on a 'pairing' twice a month on the 777, it is a desirable trip. I think the loads are high on that sector when it comes to staff travel and there are a helluva lot of EK personnel that would be in line ahead of you for Perth I would imagine.
I know very few individuals who travel as much as you envision. I do know a few single guys (and by single I include those with their family living elsewhere), who do manage to get away from here more than I thought would be possible.
Although staff travel is a great perk, and we have a fantastic network, it is not exactly cheap but that is relative to what you are used at the moment. I don't think your wife is going to want to accompany you on many of your trips to be honest. I think that novelty will wear off after the first 30 hour layover after she spent hours at the airport wondering even if she would get on the flight. I can't imagine your wife dragging along your pre-school boy and going through all of that, but that is just me.
I hope my post doesn't sound negative, just trying to be realistic. I do believe that financially you will be much better off at EK in the long-term, but I think our definitions of long-term might be different by about 5 years. I do believe that after 15 years, and taking advantage of some sound financial opportunities available here (which does include offshore investments, in real estate in particular) you will do great here. If you were single, I would cut that down to 10 years.