I had two interviews back-to-back.

Initially, I wanted to have them on-site, but I decided to do them over Skype due to scheduling problems. It was a very enjoyable experience. The questions I was asked were very open-ended, and the interviewers were very friendly.

The interviews were not extremely difficult, but they weren't a walk in the park either. The questions can be found on this site.

I received an offer at the end of the week, so the turn-around time was very quick. I was able to extend my deadline quite a bit as I was still interviewing with other companies.

Question regarding cache inconsistencies, threads, and possible race conditions. How to avoid them, etc.

They go quite in-depth in solving this problem, depending on what experience you've had so far. The fully detailed question is somewhere else on this site.

Given a building with 50 floors and 4 elevators, design an elevator controller system and code it. This is a very open-ended question.