1- What do I need to watch out for? He says the "ESN" is clean. Is there a way I can check if that is true? 2- Its jailbroken, What are the pros/cons of that? And will that give me any problems activating it at Verizon? So say everything about the phone is fine and working, do I just take it to a Verizon store, chose a plan and have them activate it?