The plugin i use for skinnable Foobar controls is called foo_looks, it's a little old and doesn't work with Foobar 0.9+, but since that version doesn't have anything better for me then 0.8.3 i still use that. There is a small tutorial for foo_looks, it's the first thing that pops up when you google for it, but if you want to do more it's really trial and error and looking through the standard skin's coding. There are a few other skins out there which coding might help a little too.
neodude. At the moment it highlights the currently playing item in your playlist, this is also what iTunes actually does (you can see this in full view), but it pops up the list as well, because otherwise you couldn't see of course. I didn't add the option to popup the playlist as well, but i could do this.