Great album on Flickr! These are truly amazing wildlife shots. Personally, I am just as interested in landscapes and scenery as I am in animals. I am adding pictures from a recent trip to Lake Nakuru National Park in Kenya.
https://www.flickr.com/photos/zug55/albums/72177720311370578/There are different ways to approach a safari photographically, and what you want to get out of this will determine the equipment you will take.
As ricardo00 stated, Africa is a big place, and without knowing where you plan to go it is difficult to give good advice. I would agree with pretty much everything he said.
I want to stress that changing lenses in the field is not advised because safaris tend to be dusty. So I would take two bodies, each with a dedicated lens. I use Sony full-frame equipment, and I put my trusty 24-105mm on one body and the 100-400mm GM on the other. I also have the 1.4x extender that gets me to 560mm. (The set from Lake Nakuru that I posted above was shot entirely with these two lenses.) You want to have a standard zoom because often animals get very close and because there are ample opportunities for great landscape shots.
Your 150-600mm lens (300-1200mm 35mm equivalent) would be great for birding, but probably too long for everything else. For all practical purposes, 600mm (full-frame) probably would be enough reach, certainly for larger animals.
Traveling during rainy season can be tricky (depending on where you go). Roads can get impassable during heavy rains. (I just noticed that you mentioned South Africa in a later post. There, roads tend to be a little better, depending on where you go.)
There are many safari threads on UHH--I would take some time to dig them up
Great album on Flickr! These are truly amazing wil... (