House2House answers some frequently asked questions about house churches (or as they call it "simple churches"). Although I disagree with some of their ideas (such as no need for pastors - see below), this is a helpful primer.
Earlier this month, Dan Edelen had a post about small group Bible studies degenerating into a synthesis of ideas about what a passage means. It's a relevant concern for house churches. That's why I think there is a need for pastor/elders whose function is to teach and guard the flock from doctrinal error (Acts 20:28-30).