Been meaning to post a mantis about Internet Radio for some time - used to use this on my LinkTheatre all the time. The streaming capability would be the basis of a more general streaming functionality, so I have just posted the mantis now as a feature request for Internet Radio/TV. I believe there are several apps out there that can do this based on xine, so it looks like the basics are already there, just some UI screens, a new media type and scenario need to be added to trigger the right commands...
Hopefully they will be interested in the idea and take it up as I miss not being able to just hit my favourite radio stations and not think about it!
As for your second question, no idea - I assume that LMCE only supports ogg as audio and ignores the other multiplexed stream of video...