Well to me accounts cannot be hacked unless you shared your ID somewhere in the past, these many people claiming to be hacked are 80% of the time lv 15 or under which tried to trade/sell accounts, and that is their own fault. Yes I guess someone can really HACK the game and your account, but I'm sure in that case Devs will see it and do something...
between 12 and 13 is on the First Born island, the Chosen goes to the second island a bit earlier than the First Born, if you've done the last Boss Quest on the Chosen island you are done with the quests.
And to dual someone will count as nothing, just a normal pvp, I'd like if you move to another area like if you go to arena, except this is 1x1, and you don't get any points for a win/loss, thus people will still do arena for the rewards (in case the devs are afraid of loosing arena sales)