Good on trading but i don't think i believe the oneshotting, it will be inevitably back even if it wont be at the beginning (and to the credit of PoE 1 they also did it as late as atlas with Sirus being biggest offender).
Tbf, technically POE1 has no oneshots per se. Some bosses have moves that do a shitload of damage, but it is possible to build a char that can tank it. Sure, it is unaffordable for almost all players, but it can be done.
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.