1. I thought it was scalable?
2. There is, /msg I believe.
3. This would be useful for co-ordinating team actions prior to starting a match, and should be included.
4. This could be a useful feature. However the whole "Friends" system is broken and needs major fixing anyway. What we need first is notifications for when someone logs on, more detailed information about where they are in-game, and notifications for when they, you know, send you a message.