I'd like to take a stab at making a very basic play/pause/next/pick playlist page (to control an empeg linked to a stereo), but I'm a complete newbie and don't want to waste time if there's something deep that would prevent this from working.

You do not need to have XML to do those things. Regular HTTP commands to hijack will do that. Check the source code to CharcoalGray's pages to see how they work.