@oposky1982,
i think we shouldn't be too careful so as not to loose a good offer. as far as i can see from the offer and job descriptions you have not been asked to pay any money as an acceptance fee like our scammers do so why can't you just play along and see where the whole thing will end. check all the procedures and do what you are asked quickly before one of the scammers decide to officially do the confirmation on your behalf and forward the acceptance through their own box with a good excuse for the new email address to the company.
i wish you all the best and keep the house posted.