Unless you're set on staying on Disney property for your vacation, it's probably more cost-effective to stay off property. With your size of group, it would be a pretty hefty expense for hotel alone. The prices are dramatically lower, and you can find just as good or better quality staying off-site. Since you're only planning on two days at Disney parks, the benefits of staying on site (transportation, free parking, Extra Magic Hours, etc) aren't really worth it.
As others have said, there's no need to leave the park to eat a packed meal. Disney doesn't care if you bring food in and eat it there. There are plenty of benches and tables that you can sit at around the parks and eat.
As for the Fast Pass thing, there's no extra charge for that, and depending on what rides you book them for, it can save you a LOT of time.
