As far as I know if you want to watch people who are streaming to the community you just need to check on the page I linked above and it will show any channels that are currently streaming.

And when streamers go live there is now a new option on their twitch dashboard that allows them to select a community to stream to and they can type in FFXIV_JENOVA to stream to the community.

Unfortunately I don't think there is a way to join the community or to get notifications when someone streams to the community. Maybe there will put that in the future. Twitch committees are still a very new thing they are still trying to work out.