Hey Glen! Good to hear from you and glad to see you're going to Africa.
Coming in by land, S.A was easy. Stamp the Carnet and go. Just a few minutes.
I do seem to recall that there is an insurance policy that is required and good for most of southern Africa. You can get it at the border of any country that it is valid for. I never got it.
There is some kind of an agreement between S.A., Botswana and Namibia where they stamp your Carnet at whichever one you enter and then not again until you leave the last of those three countries which is a little strange.
Things are pretty modern and efficient in South Africa and everyone speaks English, so it's not a difficult country to travel in. You're gonna love it.