Hi there
I think the 'isolated' and 'boring' thing is totally overplayed in relation to Perth (and I say this as someone who would never have emigrated to Perth had DH not gotten a job there, so I think I am objective). Yes, there are lots of things to do, and because Perth is so isolated people work quite hard to set up cultural activities. For example there is an amazing foreign film festival in the outdoor movie theatre at UWA all summer long; a friend has just started a second symphony orchestra in the city and they are planning summer concerts; nearly every big international act that goes to Australia stops in Perth. It is still, after all, a city of nearly 2 million people! Standard movie theatres, museums, health care etc!!
Lemousquetaire, I think you are the sort of person (well travelled) who would carry on travelling and so won't feel the isolation. But is this permanent or not? Bit confused about that. ALso think that you really need to see it if you are thinking of going for any length of time.
I meant to write yesterday to say that while I don't think Perth is boring, the suburban bits of Perth are VERY suburban - places where people live, often to be near (admittedly amazing) beaches -- rather than a place you would go to work/go out to dinner etc. As a result they are not pedestrian friendly, and not 'buzzy'. If that's what you're looking for it might be worth the compromise in space to get something closer to the city, ie Subiaco, Shenton Park etc.
Your tax situation will differ greatly depending on your visa situation (company sponoserd or state sponsored, permanent or temporary). If your DH has a good job and you are also looking the salary will match the cost of living.
The non English expat community has grown exponentially because of the mining boom (it was TINY before though). I was floored to go to the local playground to meet a Swiss mum back in August. She was also floored to chat to me in French but she said there were lots of expat activities and a French playgroup.Private schools all have v good languages but I am not aware of an international school as such. I'm not sure how much better that would be in Sydney (it's bigger, but the economic growth in Perth is higher and attracting more expats at the moment)
Local primary schools are excellent; quite a significant number of people leave the state system at age 11 for private schools but this differs enormously according to area in which you live (some have excellent state secondaries, and accordingly high house prices). I would say it is much more the norm for children of professional parents to go to a private high school then it is in Canada, where it is very unusual, but not necessarily different than the UK.
How serious is this plan?