it's totally up to you to social with existing coworkers, but not the other way around. They will come to chat with you if they are really, really nice, but in general, nobody knows  you unless you introduce yourself to the guys.

don't be shy about asking for guys to grab lunch. It's really no big deal at all. I asked a guy out for lunch in my first day because other ppl were out for a conference. He paid for the lunch, we chatted, and then I bought him coffee and bronies, etc. later on. We are now buddies. It only took days for me to get familiar with a couple of other guys. when it comes to work, personally I don't think gender matters. They are all my coworkers, men or women:-) Don't worry:-)