OK...
Hong Kong is indeed "part of China", but it's still very much a separate case from Mainland China.
It's rather hard to find work in HK, especially in comparison with the Mainland.
- HK has much higher requirements and expectations; your MA in Education will help. Do you have an active teaching certification from the USA? That'll help a lot, too.
- HK has a higher proportion of English speakers, raising the competition level.
- Lots of people, including me, want to live and work in HK, also raising the competition.
Life in Mainland China can be relatively cheap, but HK has a cost of living (especially housing) second only to Tokyo. It's quite possible to find a "good" job there that doesn't let you live very well.
I'm telling you these things not to discourage you, but to let you know there will be tremendous differences.