Yes, that's correct. The President has considerable executive power. His cabinet has to come from parliamentary members, but otherwise he is free to choose.
Once established as the way government works in South Africa. I suspect we will see the rules surrounding MONCs to be tightened like a noose so you won't have it in every sitting. That's really up to the speaker though. Which is another interesting election.
We might end up in a situation where the ANC agrees to have a DA speaker, with an ANC president and strengthened rules surrounding MONCs. That's the kind of DA/ANC coalition we're likely to see if it is to happen.
TL;DR. We're not like the Netherlands where you can have a technocratic interim government. Once the first seating of parliament takes place the president must be elected in the same sitting.