Hi Krystal! Welcome to the Disney Parks Moms Panel. The Standard Dining Plan is a great option. I always find that it is the perfect amount of food for my son and I when we travel. You are correct in that your family of 4 has 28 Table-Service credits, 28 Quick-Service credits, and 28 Snack credits total to use over the duration of your 7-day trip. You can only redeem Snack credits for snacks, just as you can only redeem Quick-Service credits at a Quick-Service restaurant. The only exception that I can think of is that you might be able to use a Table-Service credit at a Quick-Service restaurant. Always check with the dining location beforehand to be sure they will allow this exception.
Along with the dining entitlements, you get a fun refillable resort mug. We have a collection of mugs and we love using them at home. Actually, I am sipping some hot chocolate from a mug right now as I type!
After you check-in at your Walt Disney World Resort, you can use your individual credits however you please. For example, on your first day, you can use all of your Snack credits if you wish. You can use more than one of your Quick-Service meals per day, or any other of your
Dining Plan entitlements to your heart's desire until they are depleted.
I hope this clears up any confusion, and feel free to come back and ask any other questions that you might have.
Have a magical day!