The system is automated, meaning that once slots are available, beta testers will be chosen, without any beta key to speak of. Kaivax then goes to stress the importance of your account security, stating that, “any third-party e-mail messages, websites, or in-game whispers that offer beta keys or access to the WoW Classic Beta should be considered illegitimate and ignored or reported.”
Things like Tauren melee reach being bigger, which is something I experienced going away live during Black Temple Illidan progression (at least for that particular encounter), is confusing to players as it's a significant advantage over other races in some instances. No quest tracking is another apparently confusing issue, as many Mankirk's WIfe seekers well know, and there's a whole lot more where that came from:
Hey! Just came back from the game, looking to play bfa but i had no idea what to do when i logged on. It was all a bit confusing and i know nothing about the current content. So after some frustration i bought zygor again (haven't used it since cata ..) and i do currently feel more comfortable. I'm following the guides from the 'suggested' tab in zygor but i'm just really unsure if what i'm doing is even relevant. I know the end of the expansion is coming so i'd hate to waste my time. OK i will list the things it's been telling me to do.