I have always purchased them separately but am not sure this is the way to go.
My husband and I have an annual pass so we get the room under the AP code.
We purchase tickets for our kids through mousesavers.com link and have found this to be the cheapest deal. Really it's only a few dollars cheaper.
I have never been part of the meal plan only because it wouldn't make sense for us. My daughter is vegan and it's a chore ordering meals for her so we visit a local grocery store for her, and the rest of us have only one main meal a day, snack in the morning or evening. I believe there are others who like the no-fuss of having a meal plan knowing that all of your meals are included.
Good luck in whatever you decide to do. Hopefully someone with meal experience will respond.