Barcelona's one of my favorite places in the universe. As MB has suggested, an internet search is always the best place to start when looking to explore what a place you've never been to before might have to offer.
In my experience, the guys in Barcelona are usually very attractive, friendly and outgoing, but English is not spoken as universally as, say, Amsterdam or Berlin. Unless he's Jewish or Muslim, your chances of his being uncircumcised are very, very good. Your best bet would be a sauna (bathhouse), not a bar, where conversations are generally kept to a minimum.
But, as fabulous as Spanish men are (and they really, really, really are), if all you're going to look for while in a city as rich in culture, heritage and architecture is cock then your trip will be pretty much wasted.