Though I said before that I don't know anything about the bike scene, much less the fixed gear scene in Berlin, I have been there and I will say that it is my favorite city in the world besides my own. You will have blast, no doubt. Work will be a problem, apart from the work visa issues there is little work to be had anyway - but it is very cheap to live there, in Kreuzberg you can get a really nice 1 bedroom apartment for like 200 euros a month. As for English, yes, most Germans do speak good English, at least those under the age of 45, however, you really should learn some German if you want to get around, and definitely if you want to make any friends while you are there. I took German for 2 years in college before I went and it made all the difference. Even if what you are saying is not 100% correct, and even if they just respond in English because they realize you're an Amerikaner, they appreciate the effort, and will generally be helpful. And I'll say once again, I'm jealous.

Check out the club Tresor. It's ridiculoid.