Hi Please guide me on how to obtain a visa for my cruise from Hong Kong to Singapore-South African

Mi itinerary is as Follows: Arrive Hong Kong 15.3.2017 until 18.3.2017. Arrive for the day at Keelung Taiwan on 20.3.2017. Cruise to Shanghai 22.3.2017. Cruise to Busan S Korea 24.3.2017. Cruise to Nagasaki Japan 25.3.2017. Cruise to Seoul S Korea 27.3.2017. Cruise to Shanghai 29.3.2017. Cruise to Hong Kong 1.4.2017- at sea from 2.4.2017. Arrive for the day of 5.4.2017 to Bangkok and then arrive in Singapore on 7.4.2017
From this itinerary I need a multiple entry visa into Hong Kong as I am there for the longest time- please confirm that I am correct. I wish to apply for the visa personally in Durban. What documents do i require and how early can i apply as I have already paid fully have have all my tickets? What is the cost? - R700 +R400?