Documents for HK and China Visa process.

Dear Sir

My family needs to visit China and Hk. As I know I need to submit below documentation.

1 . Passport
2. Bank statement
3. Invitation letter.
4. Photos.
5. Application form.

A ) Do I need submit any other documents?

B ) Invitation letter need original one or copy is ok ?

C ) Can I apply HK one also in China embassy ?

Thanks a lot.