Regarding spam: why don't you block posts where the title is an URL? A large chunk of the spam has a link for the title (and virtually no normal posts does that).
I’m actually not sure this is possible without writing a custom extension for it, but if you know of one, it may help slightly. Unfortunately, spammers have gotten much better at dodging traditional methods for spam detection so that most built-in ways of dealing with it (at least, ones not requiring manual labor) don’t help. The most common type is human users who post a single message that might be able to pass off as a regular post, except that they include links in their signature or profile field which are meant to be indexed by search engine bots to increase the “credibility” of their site to the search engine, thus improving their search ranking.