We know you’ve got questions, so ask away, and we’ll try to clarify where things are hazy.
Not a question, just wanted to state my disappointment about the invites. I know it's my own fault for imagining what BG would be, but in my mind it sounded like a great solo challenge. Something a player could do on their own (ie not need a guild and a raid schedule to enjoy) via doing instanced solo challenges. Instead there is going to be a long period when only the folks with money to access the BMAH can get invites, and then will be sending them to their guildmates and friends. As someone who doesn't have that kind of gold, and isn't part of a big/progression guild I can currently see no path to get myself into the Brawler's Guild based on the description you've supplied.
What sounded like an opportunity for solo players to enjoy a challenge instead is going to be locked to them for flavor reasons.
As for the "one at a time" thing, I'm not sure how being able to watch the fights provides more of a reward than having them be instances so you don't have to wait in line.
I dunno. I just feel deflated by the implementation of what sounded like a fun new feature someone like me could have access to.