One of the biggest and most telling of the hiring stages is the interview. As much as your questions are needed/required to get information from a candidate, there is a lot that can be gleaned from the subtext of their answers.
The most common interview questions are:
What would your previous employers want to change about you?
What do you think management should do to allow you to function more effectively?
What has prevented you from progressing as fast as you would have liked?
Tell me about the best and worst boss you've ever had?
What was his or her management style?
What have you been doing since you left your last position?
Why do you want to leave your current position?
The responses to these questions can give you a lot of information about your prospective employee. Did they frame their responses in a positive manner? Did they research your company? Will they be able to jump into the position and begin right away, or will they require a lot of hand holding and training? Do they add to the question with essential continued research and industry knowledge or are they attempting to fluff over this crucial information?
There is really no more stressful situation than the interview. Companies want to hire competent, successful, and articulate executives, yet the candidate's first introduction to the company is a particularly stressful and uncomfortable situation. Needless to say, you will need to allow for some nerves, but stick to the important facts of the position.
On a final note, define your interview process in advance. Is the interview process one-step? Is there a phone interview before the face-to-face interview? Is there a panel-interview before/after the initial interview. Communicating the interview process to the candidate effectively will help to alleviate confusion and will lead to better use of interview time for both sides.