Is my new work friend gay and is he interested in me?

I just started a new job this week and immediately met a guy who I think is very cute. I am not in the closet, but I am also not clearly gay. The guy and I started chatting over the work IM service and do so pretty often throughout each day with both work topics and also goofing around. He is a naturally nice guy, but I do think he likes to talk to me at least a little more than other people in the office. I've also heard him say to other workers that he's glad that I joined the company because I'm american and he spent a number of his childhood years in the US and he like to have american friends (our office is in sweden). Yesterday he went around the office and single handedly invited a bunch of people to hang out after work. About 12 of us went to a park and had some drinks, and he spent the majority of the time near me talking in a group. He also touched my shoulders a few times while standing-up and sitting down. He invited myself and 2 girls to stay over at his apartment since he lived in the area and we all lived in a different city, but we ended up going to our respective homes. I really like him and would like to continue and see where this goes, but I don't want to make a fool of myself if he isn't gay and is just being nice. I'm thinking about telling him casually that I'm gay and see what his response is? Any thoughts as to if he's interested in me and how I should proceed?