Cambodian applying (business travel) multi-entry visa for Hong Kong and PRC

Q-1: Is it possible for me to apply in Malaysia PRC Embassy?

Q-2: Do I a Cambodian need one for Macau before visiting Macau?

Q-3: Is it possible for me to just apply multi-entry for Hong Kong? Each en

Q-4: How many days can a Cambodian stay in Hong Kong if a multi-entry one is obtained at the Malaysia PRC Embassy?

Thank you.

Thoeun