I take it you're not in England, or you'd have to worry about the Public Entertainment Licence stuff. But I gather there can be problems like that elsewhere, so that's another thing to check.

"Basements" sounds like it might be a problem for access for some people. You ought to avoid landing in a place where people in wheelchairs and their friends can't use it.You'd be potentially keeping out some great musicians in my experience, aside from anything else.