Sorry! No addons (unless some are made specifically for the new release of Warcraft Classic). Also, Bidding Is A Thing. There were bidding wars for the most expensive items on the AH, which you can only find in IF and Org. There might be bidding wars for the rarest of items on trade chat or the realm forums, for things such as the Hide of the Wild pattern. This drops from Dire Maul, Knot Thimblejack, by the way.
The notion of ongoing updates as they originally appeared, though, raises the question of expansions. Blizzard has released seven expansions in all. And while later ones like Legion or Battle for Azeroth would feel out-of-place within the Classic framework, it stands to reason that some players may want to experience earlier expansions--such as The Burning Crusade or Wrath of the Lich King--in the context of World of Warcraft Classic. Blizzard isn't committing to this, but also hasn't ruled it out.
As many of you know, leveling a Warrior in Classic is not easy - it’s almost like playing the game on hard mode. Despite having low mobility, low sustain, and the highest gear dependance in the game, Warriors are by far the most played class in Vanilla. There is a sort of masochistic appeal to leveling the hardest class in the game. To some, this epic challenge provides the purest Vanilla experience, and watching an expert pilot this class with finesse is like watching an artist at work.
Even though a modern server architecture is used, Classic servers won't have the same features that current World of Warcraft does. There won't be cross-realm servers or Looking For Raid and Dungeon Finder automatic party matchmaking. There are still a lot of questions about how the team will tackle it. This endeavor is being undertaken by an entirely separate team at Blizzard from the one working on World of Warcraft and its next expansion.