Want to change Steam account region to China from USA. Consequences?

Yes, in account details below where the country is shown.

Yes.

Probably, USA isn't region locked but China I understand has some issues with censorship?

To confirm the store country change you need to buy something using a local payment method so if you intended to use Steam Wallet there will be a delay while you do that.

1. Yes
2. Setting your store region the china doesn't automatically mean you can activate Chinese games. You Still need a Chinese IP.
3. Yes.
4. No, but you would need a payment method registered in China before you could purchase from the store,
5. Once you change store region, you can't change back for a month.

5 I'm pretty sure if you move out of China later in your life, you won't be able to play the games you bought that in China.