I found through experience that most of the important questions tend to be missed.You will be able to find out if they know how to do the job by asking them a series of technical questions and give them a test. But how well are they going to work as a team or around residents.I found the best workers I have hired have been the ones that are really interested in helping others and are goal oriented.
Try and ask behavior based question.
1.Why do you want to work for our company?
2.Do you feel you work better by your self or around others?
3.Where do you see yourself in 5 years?
Make sure you go over these questions with your manager and HR so that they do not conflict with policies/procedures that your company may have.Also be fair try and ask everyone you interview for that position the same questions.
Here is a helpful web site with a list of more questions.
Hope this helps