What's the most respectful way of asking my classmate if he's interested in men? Guys can be so confusing.

I had a couple classes with this guy last semester. He's 100% my type as it comes to personality, looks, interests, etc. One of our classes together was small, and we'd always sit in the front. Throughout the semester I noticed he'd check me out before, after, and during class. Of course, I couldn't resist checking him out too. Fast forward to this semester, and we have another small class together. I sat diagonal to him and noticed him turning his head. Again. Me.. following suit, of course. We walked and talked after class. Next class, we walked and talked again except that time he asked for my number. I've seen him since, and it seems we're becoming friends. I'm done looking for signs and such. I want to ask if he is gay or interested in men, but I don't want him to feel pressured or uncomfortable. He's someone I'd want to be friends with if he were straight. I thought about just asking him to grab lunch after class and seeing where that goes. He already threw out ideas for things we should do when the semester is over, which is some far out planning if you ask me considering the semester just started.