How exactly does the Gurubashi Arena Booty Run work? Is this PvP, like Warsong Gulch? Every 3 hours, you have to fight everyone?

What kind of loot is in that chest?

check thott for the loot table, but the big one for most people is there is a trinket (Arena Master) that starts a quest to collect 12 arena master trinkets and turn them in for a Grand Arena Master trinket, which looks pretty nice.

Its not capture the flag like WSG, its more like last man standing. You can try to loot the chest anytime, but you will get interrupted if anyone around is still alive and sees you (takes a while to open too).

You can take some friends and go as a group if you want to improve your odds. watch at the end for the stealth attacks. On my server there are always a couple rogues/druids that are waiting around stealthed for everybody else to kill each other, and then when the last couple of guys go for the chest they sap or whatever and take it from them.