There is an auction house for currency-like items only. You get gold coins from killing monsters. Gold coins are not tradeable with other players. The auction house allows you to exchange orbs for other orbs, fragments, or other currency-like items. The auction house charges gold coins per transaction. So your auction house usage is limited by how many monsters you kill. You still have to trade other players for wearable gear items.

The boss fights are now intended to be longer but more rewarding.

I also heard that they are now limiting players to 1 death per map. If you die to a boss, you lose the instance.