HK is very expensive (recently ranked the most expensive city in the world). A decent apartment costs a small fortune. The further away from central you get the more affordable it becomes. You won't be able to move here without being sponsored for a visa/work permit. With that said, I have no idea why anyone would want to relocate here without a well paying job. I'm sure if you looked you could find a roomate. AsiaXpat is a good place to start. When in HK also look for the "HK Magazine" personal section which comes out every friday. The income tax is 15%. There is no catch - except if you are a US citizen, you are taxed globally after around the first 80K USD in earnings. As for China, unless you are fluent in Mandarin and again sponsored for a job, it would be tough to move there. Shanghai is booming and there are probably opportunities.
Internet and Telco infrastructure are excellent. Much better than Australia (sorry zen). Broadband would be about $50 bucks a month.
Australia: Great place to live (Sydney & Melbourne) - horrible trading hours if you want to trade the US. also horrible taxes. I'd be tempted to move our Asian operations to Sydney if it weren't for the taxes (corporate and personal).