You can submit your applicaitons to HK and China to Chinese embassy with following docuemtns:
1. Visa Application Form for Hong Kong;
2. Photocopy of page 1-3 of your passport;
3. Residential visa/permit in other countries (if any).
4. Proof of financial background /employment, saving account passbook, bank statement, tax receipt, etc;
5. Employment certificate, or business registration;
6. Invitation letter from business contact in Hong Kong, or proof of participation in trade fair or conventions, etc.
The general processing is 4 weeks if connection with HK Immigration is necessary. Visa processing to China takes 4 working days in general.