As far as resizing 4:3 to 16:9, Trevor Andrew has written an excellent tutorial on this subject available here...
http://uk.geocities.com/trevor.andrew@b ... vs/all.htm
I would strongly recommend giving that (and the rest of his site) a read. He's a very knowledgable guy, and explains things in a very straight forward fashion (much better than I could hope to).
I don't often use the WMV options so I'm afraid I can't help on that front, sorry.
peace.