Yes! Do it! I would love to see you and the family here :D
1. Healthcare is OK. Maybe not to Singapore standard, but our public system is pretty decent. You're healthy, assuming the family is too, I don't think this needs to be a major consideration just yet.
2. Any of those. Of course I'm going to say Melbourne, but all three cities are very nice. I think KL and Melbourne have some things in common - they are cosmopolitan, vibrant etc. Bear in mind that Melbourne gets *very* cold for 4-5 months of the year (by your standards). Perth gets revoltingly hot for 2-3 months between Dec and Feb. Your little ones might find it too much. Sydney's weather will be closest to what you're used to.
3. The market is what we euphemistically call "unsettled". With your background I can't see any major hassles finding work, but then again, I've been unemployed for three months and I never thought that could happen to me
Probably best to scope with your employer before you consider moving.
4. Yeah, Australians love this kind of stuff. I remember you were talking about importing furniture a while back. There's still a solid market in that here. I suggest coming here, working for a year or so, getting a feel for the place and then putting something in motion. More than happy to help you out with this.
5. Yes. I think your family would love it and the worst that can happen is you have to go back.
I guess my questions (based on the fact I know you outside of BL) are:
- Would your wife have enough here to keep her happy? Work/friends/raising the kids? It'd be a shame if she was bored and it's a long way from your family.
- Do you want your kids to be raised in a Western culture? There are plusses: they'll learn English from native speakers, and it's a very nice, safe country (mostly), but they might experience some racism that wouldn't be a consideration at home.
But still! Do eeeet! :D