You do need a carnet (unless there is another way to import in to RSA without one perhaps, though mine wasn't stamped in actually). The shipping company kept hold of mine and sent it to me once they were finsished with it (the carnet).
I think they took a photocopy of my passport. But otherwise, that was about it.
I gave them the measurements I estimated, but as I said the final weight was quite high - higher than estimated so the price went up a bit, so if considering then just remember this.
The company let me drop the bike off at their warehouse near the airport and then drove me over too! Admitedly almost missed the plane, but still the thought was there.
The ship was slightly delayed, one week or something. On the pick-up side [in my case; Korea], good idea to have some proof of value for customs. So the carnet is useful, or an invoice even for the bike. The Korean chaps couldn't seem to realise that all the information they needed was on the carnet, took quite along time.
Will PM the email address to you. And a few others.