I think there should be trading rooms in the OP PvP server. Many of my things have been stolen as spawn is over crowded. Trading Rooms will make it easier to trade and give stuff to eachother without the risk of clear -lag and stealers, as there should be a chest in the trade room.
I'm pretty sure trading rooms will be implemented after the ones in KitPVP are finished. If not, they should be
ClearLag will always be a risk. You just have to pay attention to the messages it throws out in chat.
If a chest were to be placed, people would fill it with their junk. It would need periodic cleaning or automatic deletion as soon as the room is left. So, if both players were to accidentally step off the pressure plate with items in the chest, they'd lose them. This is unlikely, but possible. Periodic cleaning would probably be just like ClearLag. Also, the chest would have to be placed somewhere out of reach for people outside the barrier.
Well, they're not going to be added with the current spawn. They'll be added with the new spawn so I'm sure they'll be a designated spot for them.