Unless you're on a DVC reservation, you must book a package if you want a meal plan (AP holders do have to book packages, even though they are ticketless packages). If you know you are going to get the meal plan anyway, it is easier to book the package than it is to book a room only and then convert it to a package. You cannot add a meal plan to a room only reservation. You can buy the tickets separately through Disney, but you cannot buy the meal plan separately.
If for some reason you absolutely want to pay off your vacation later than 45 days from arrival, you can book the room only and convert it to a package later, but if you don't mind paying it off, just do it all at once.
I think the family suites have a capacity of 6 persons, and the OP has 7. Unless one of the kids is under 3.
With 7 guests you would need two rooms at POR, even if one of them is under 3.