Great ride you have planned there. Please don't take JHB as the standard reference for any SA city! Come down here to mellow Cape Town, you'll find it a lot less stressful!
You have some AMAZING riding ahead of you. Good luck and enjoy every moment.
Take note of how the scenery and vegetation changes as you ride. You will be passing it all, temperate, sub-tropical, mediterranean etc, etc.
Keep left and pass right.
Bye for now