Okay, I talked to my witch co-worker briefly again. My memory is kinda fuzzy, but I THINK this is what he said about his beliefs:
Doesn't believe in harming anyone.
Believes in spells and hexes.
Closest to harming someone he can come is to hex (charm, put a spell on?? forgot what terminology he used) them so if THEY wish something bad on someone, whatever they wish will come back on them three times as badly.
Believes that if he concentrates enough and practices enough, he can visualize an object in a specific place - the example he gave was, one can think of a real clock somewhere, and continue to concentrate (or meditate or whatever; forgot terminology) on it over time, and then after a long while, if one wants to know the time, all they have to do is visualize that clock at that very moment and then they can see what that clock actually says. I have the impression that he's tried this, 'cause right after he gave that example he said he'll look at an actual clock and compare it to what his visualized clock said.
I don't quite exactly remember what else he said. We only spoke for a few minutes. I'll post more as I talk to him more. I don't see him around very often.
ETA: Ah! I also asked if there were spells to seduce someone. *grin* He said yes, but one has to be careful because sometimes the seduced person gets too possessive.