All the above can be obtained with software such as Flash Media Server (or Red5 for open source). If you want to use Node.JS, you will need to either create your Node services (message queue, media server), or use some already available, and have Node.JS handle the interaction between them. So all of these will be needed:
You can choose Flash, it has great support for RTMFP/RTMP. If you really want WebRTC, you will have to create a STUN node service for p2p discovery, which is connected to the caching service to handle authorizations.
RTMFP is an option, webrtc too. Most performant depends on how you define performance: quality? latency? how should it be biased? If you want low latency, go for p2p. If you want recording capabilities, either rtmp or a node webrtc relay.
Yes, but you will most likely need a team to do that :)
Found almost all of the answers :)