Two weeks isn't long enough for cats to get to know each other, or for him to build trust and get to know you. He's still scared from moving around and living with a bunch of strangers, he needs more time. He's being agressive towards guests because they are even more strangers, my cats certainly don't like strangers trying to touch them, I would say most cats are like that.
He might always be somewhat agressive towards you, my boyfriend's cat likes to be petted when he wants to be petted and other times he wants to be left alone. It's up to you to learn his signals and respect his boundaries.
As for the rats, cats are predators and rats are small and tasty as far as they are concerned. You need to be able to keep the rats and their cage in a separate room from the cats when you're not in the room or something bad will probably happen unless your rat cage is enforced enough to withstand a cat trying to knock it over, pull it apart, etc.
I wouldn't trust any cat in a room alone with rats in a cage they could in any way conceivably open, knock over, or otherwise get into. That goes for almost any commercially built cage I've ever seen.