In terms of what the World of Warcraft Classic Best Classes are, Warrior and Priest stand out almost instantly. This is partly due to the fact that Protection Warrior is the only viable Tank Class in WoW Vanilla Patch 1.12. Both the Proc Warrior and Priest are required for Raids and when combined in a PVP setting can be a fierce combo on the battlegrounds.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.
To actually get access to the beta, which has already started and continue to add more players, you need to sign up via your Blizzard account management page. Under Games & Subscriptions, scroll down to Beta Access and visit the Beta Profile Settings page. Once there, you’ll see a grid of available betas you can opt into. Once you’ve checked WoW Classic, hit Update Preferences and you’re set.
You create a meta where you're constantly buying gold. Gold is very important in vanilla consumables are the difference between being a hardcore raider and being a casual. The notion that wow token doesn't create inflation is incorrect. By giving every player the ability to buy gold you're increasing how much gold your average player will have. the 1% rich player who has the ingame gold to buy these tokens was not trading with that gold. But now they buy ingame time and the gold that was sitting in their pocket is now being used to trade, buy items, herbs, etc. now there's more gold in circulation. Now everything costs a little bit more gold. And if you're a player who's not buying wow tokens with real life money you have to farm just a little bit longer to compete. That's why wow token is bad.