As somone who has done a lot of hiring, I can say that if you are looking for questions to ask, then you may not understand what kind of person you are looking for. Here's what I look for (in order of importance):
Honest
Motivated
Plays well with other children
Learns well
Skills
While you may have a minimum skill level that the person must operate at, that characteristic won't be the most meaningful to you if the top four aren't there.
If someone's not honest, then you'll never know if they did the work, did it well, screwed off most of the day, etc. Its critical that someone honestly represents what they know and what they don't know.
If someone is not motivated, you'll never get the productivity you want.
If someone can't interact with others, every day will be hell. You want someone who can communicate. Sometimes you have to draw people out. There are gems out there once they feel comfortable with you.
I'll take someone with fewer skills any day if they _like_ to learn.
So just talk to the person. Ask about what they like best and worst about their last job. Ask about the toughest thing they ever did. What are they most proud of? Ask when their last all-nighter was. Ask what job they want one year from now. five years from now. Ask when they want to retire. Ask if they are a leader or a follower -- and be sure to say the both are important. Ask how long it takes them before they ask for help. Ask whether they like multitasking or are serial workers. Ask whether they like to know what their next task will be after this one. Ask them what they do when when they get stuck or reach a dead end. Do they work better alone, in a small group or in a big group? DO they work better or worse under pressure? What's the last technical book they bought with their own money? Are they a tinkerer? Are they an early adopter? What's their favorite tech web sites? Where would they go to ask technical questions outside of the company? Do they have a network of techie friends?
If you can capture your own day-in day-out experiences, you'll know better what to ask.
Have fun!