All the times that we've stayed at OKW, we've never had a problem with buses or food. The store (General Store?) has a decent selection of food including bagels, orange juice, bacon, eggs, milk, cereal, coffee, sodas, spaghetti, spaghetti sauce, snacks, beer, and even hard liquor.
The bus service is typical for Disney; don't head out of your room 15 minutes from the curtain at La Nouba thinking that you've got plenty of time. Always give yourself enough time to get to where you're going.
As for shipping food down yourself; this is an *excellent* idea! We've never done that, but we have used Tiffany Car Service and took them up on the 30-minute stop at Publix on the way from the airport. We're doing that the next trip when we stay at the Boardwalk Villas.
Have a great time!