https://www.twitch.tv/team/firstchamplive
The official streams came from twitch with each field getting its own channel. RoboSports Network (Game Sense at the time) also had a stream running on twitch and youtube I believe that bounced from field to field with commentary and highlights from major matches.
As for live viewers, I don't know off hand. There's probably somewhere that archives the max number of current live viewers on a twitch stream though so a bit of investigative googling may yield that answer if someone here doesn't know.