You don't have to book the Candlelight Processional itself - general seating is free. It's a beautiful performance with a celebrity narrator (official list of narrators for this year has not been announced) reading short passages telling the Christmas story with a wonderful WDW choir joined by visiting choirs singing between the passages. It's absolutely beautiful.
Many people (me included) opt to do the CP Dinner Package. The lines for general seating can be very long, and the CP Dinner Package includes seating in a very nice section front-and-center. The list of restaurants and the prices for this year's dinner package have not been announced yet. There are 3 performances each evening from late November to early January. With the dinner package, you choose the time that you want to attend and WDW Dining will tell you the dining times that correspond with that performance. In the past, there have been three price tiers of dining options, with buffet-type restaurants like Garden Grill, Biergarten and the Restaurant Akershus in the lower (less expensive) tier and other Epcot restaurants in the upper two tiers. The package also usually includes a 15% discount at Epcot shops for the day of the dinner package, but I'm not sure if that was included last year, I think I read somewhere that it wasn't.
Keep watching the DIS Boards for news that Disney has announced the CP narrators and dinner package, then call and make your PS if you choose to do the package.