[cata cross real]

Arena is dead on warsong, PVP too.
Is it possible to cross realm both cata server so we cab have more PVP for both realm ?

no, this is not a posibility at the moment. first of all the clustered load balancing should be in a state decent enough to handle this. then after that, the whole crossrealm thing itself would have to be scripted. since last time I heard CLB was mainly a wotlk project, I am not too sure if it will be coming to cata in the coming year.