Yes you use your key to the world card for the dining plan. Everytime you use the card for a table service, counter service, or snack the receipt will show how many you have remaining for that category so it is very easy to keep track of.
It is a TON of food, desert included with both table and counter - wow. I thought it was definitely worth the money but you have to make sure that you use all of your table services to make it so. You will need reservations, we made them the day before since we wanted to be able to plan our days as we went.
You can also use them in any order, if you wanted to have 2 table service meals for 3 days in a row you can do that. The only drawback IMO was the amount of food, even with all the walking I think I gained 10 pounds.