Hello, I am a BANGLADESHI OFFICIAL passport holder. Do I need Chinese Visa to visit China ?

I am studying in south Korea by Korean Government (KOICA)scholarship. I have already bought air ticket INCHEON-HONG KONG-DHAKA with 5 days transit in Hong kong. During that 5 days I want to visit Guanzhou province (in mainland , china) by Train, then return to Hongkong and again from HONG KONG to MACAU by Ferry and return back to Hongkong to catch flight for DHAKA. My three questions are as under:
1. Do I need Hong Kong Visa to enter in Hong Kong? 2. Do I need Chinese Visa to go (Guangzhou province)China mainland ? Do I need Hong kong Visa again After Visit China mainland? 3. Do I need MACAU Visa?
WAITING FOR YOUR KIND REPLY.........