Rohit really was made to look a bit amateur at the start, was like he was playing a whole new ball game when Steyn was bowling at him, got cheers just for getting bat to ball. He is very talented though and seems to be stronger mentally, so I think he will get through it.
Kohli looked decent, has the technique and skills to combat SA on these pitches, though very lucky with the drop catch from the keeper. I think in general these guys will have to work out pretty quickly that some of the shots they took for granted back in India are just not going to work in SA.
I think Yuvi is finished, it all looks a bit apathetic from him sometimes these days. Raina is another weak link, though maybe because he can bowl and is a great fielder he has some other ways to contribute. Plus he plays in the Super Kings, so I doubt Dhoni will let him go. Rahane might hopefully get a look in at some stage, I don't really see how he can be any worse than these two.
Bowling - I think Umesh should come back but maybe they are saving him for the tests (I don't really agree with this policy but hey). Hope they don't decide to bring back Ishant or Vinay kumar though, they are as dreadful if not more.