@ Chocoswiss,
I was in the same boat as you are. I gave the interview by VC. I have now been asked to attend the AD. I am not sure what their criteria is to call candidates for AD.
As for interview, it was nice. I was interviewed by an alumni who was working in the adcom. There were very few questions related to work etc. Most of them were related to what i did in school, why did i come here (my current work location) most memorable moment of school life, why IESE etc etc.
A few things that you should keep in mind is, get a good quality VC service. Make sure that you have a onsite technician available. In my case, there was a problem as a result of which, they could not make call. Eventually, I ended up calling them
but since there was a technician available, all this issue was resolved within 10 - 15 mins.
Many facilities (atleast here) did not have a technician available.
Also do read your essays and resume before hand. The last thing that you want is to contradict yourself (my interviewer was had my resume with her and had done a very thorough analysis of my essays and resume and was well informed).
HTH and Best of luck!