When I was single/dating, I always liked the somewhat vague expression "I'm seeing some other people but I haven't really settled down with anyone." It leaves room for feelings to develop between you and him, and it tips him off that you've got some things on your plate that may push him out of the running.
As for "figuring out" if you have feelings for him, you hit the nail on the head. In the past, I dated some people who "seemed" like they should be perfect for me: same interests, they were attractive, similar politics etc, good conversation... but nothing "clicked" and it was really hard to admit that they just didn't "do it for me."
You also want to be careful of being too presumptuous. It would be embarrassing to say "I don't have romantic feelings for you, but I'd like us to be friends" only to find out he was only asking you out as friends to begin with.
In my past, there's always been a very clear point where things started moving into "more than just friends" and you don't want to get much past that before making up your mind and letting him know how you feel.
It's 2010 and you're in university. IMO, there's an unspoken rule there that everyone is just dipping their toes in the waters and experimenting, and that all relationships are pretty much friendly and casual until declared otherwise. I don't see any reason to jump right into a decision or announcement. RP's rule definitely works for her life: she's a married parent with other partners. She's not looking for that university-casual dating thing, she wants close emotional connections. You may long for those also, but you have your triad plus all the time in the world to settle down
As for your triad getting back to her family, I would feel out his trustworthiness and tell him before it gets serious. If you think he would spill the beans, then he probably isn't someone you want to be with anyway: trust is important and if you don't have that, you don't have much.