Well it will be released after Warsoc, which allows up to 50 players I believe (Could be more) to play this single player campaign together. Basically a huge custom map.
To the "Will it be able to keep track" The prices will be set around the prices they were at on the original WoW, twink gear will go for a lot higher price, items that were rare back then will go for the same price as well. You're complicating something that is so simple lol, the rare stuff will of course be pricey, linen etc... will go for a decent/low price, then so on and so forth.