Firstly you will have a ball, Namiba is a great place, great people, awsome beer, UNBELIEVABLE HUNTING!!! Id move there.
All of the animals you have listed are no different to all the others in the world the vitals a more or less in the same place.
Hitting the shoulder is a favorable idea, mechanical damage is a must, YOURE NOT THERE TO HARVEST MEAT! Hit em as hard as you can.
These animals are tough critters my Hartebeest got hit with a 338 Win Mag highish shoulder it dropped on the spot, then got up and ran and ran and ran.
That animal got hit no less than another 7 yes 7 times with a 458 lott after the 1st shot with the 338, the guide told me they were tough, holy cow!!
Just to get you excited
My list was
Jackel,Gemsbok,Warthog,Impala,Kudu,Springbok,Zebra ,Hartebeest, and Blue Wilderbeest oh and a Baboon.
All the best for the hunt it will change your life.
Any other tips for african travel of what to do just PM me, more than happy to help.