Brad Choate's MTMacro plug-in (http://www.bradchoate.com/past/mtmacros.php) ought to accomplish your first wish. Don't know of a way to do the latter, though.

Cross-posting really should have been at the top of the list. I would think there would be _enormous_ demand for this, and it strikes me as _the_ way of leveraging the power of MT as a Web publishing _system_. Many times have I wanted to cross-post between, say, my main blog here and a course blog.