Amanda,
First of all, there are great PDFs that you can print out of the different
dining plans on the Disney World website that can answer a lot of your questions. But the dining plan does not mean having to make reservations for each meal.
It is a plan where you essentially pre-pay for some of your dining, and get a discount for doing so. You order the plan, and get a certain number of "credits" for meals and snacks. You redeem these during your stay whenever you please, at whatever participating restaurant you choose. The Advanced Dining Reservations are just necessary to ensure you get a table at a specific restaurant, particularly if it is a probably one.
The plans are almost always a good idea for a group traveling to Disney World. The real question is do you go for the Quick Service plan, the Standard, or Deluxe? You can decide based on your what your dining preferences are.
I am glad to help with more information on the plan, if you need. Just send me a follow-up question by going to my bio page!
Have a magical (and delicious) vacation!