Related to this, we’ve seen a lot of questions about the general invite process and want to clarify a few things. The method in which people are invited from the opt-in pool is not on a first-come-first-served basis, but instead we look at a variety of factors such as the age of the account. That said, the amount of closed beta invites that we’re sending out is rapidly decreasing as we have met our current population needs for testing. We’ll regularly reevaluate the need for additional invites as we go through the testing process.
It seems the first stress test didn't quite do the job yet, as Blizzard are scheduling a second one next week, due to more issues with the first one than were anticipated (mainly of the login screen variety). Everyone that was invited to the first one will also be invited to the second, the level cap will be raised to 10 and it will also be available for a full day, starting at 2pm PDT on Wednesday, May 29th.
Most people come here not to read walls of text, they look for the better-rated strategies that match their pet collections, copy&paste stuff they need to import into their addons and only come back if something goes horribly wrong and then mostly to find help in other peoples' comments who also struggled or to find a different team/strategy: I don't think many people wanna read about stuff that already happened to them, they mostly want to see solutions and it's the best way to have them in a well-optimized strategy&team already.
2. Achieving. There are many pet battling achievements in game, and following the natural trail through the Taming [Continent] achievements up to Pandaria, and then on to the Spirit Tamers, Beasts of Fable and the Celestial Tournament was an epic journey for me and for many others. It's well worth doing. The Celestial Tournament is still, IMO, the pinnacle of PvE pet battling. However, WoD and Legion and BfA have added more battling achievements.