The way the Candlelight Processional package works is confusing.
The way the package works, your seating will be before the Candlelight Processional, which will be before Illuminations. Depending on which seating/show you choose, you will have varying amounts of time between the end of the candlelight processional and Illuminations. You would not be dining at the time of Illuminations, so viewing of the lagoon to see the fireworks is not a worry. In addition to your guaranteed seating for the Processional, the package includes access to a special viewing area for Illuminations (the fireworks show at Epcot) at the bottom of the lagoon directly opposite from the American Adventure, which is the primary direction from which the show was designed to be seen.
If you choose to dine during Illuminations (not through the CP package), there are two restaurants that provide views - Hacienda de San Angel and Bistro de Paris (limited). If you are dining in a restaurant that does not provide a view, you are able to leave, see the show, and come back to finish your meal.
The Coral Reef is located in the Living Seas Pavilion. It has only one view - the aquarium. Not the lagoon, but not shabby either. The restaurant receives very mixed reviews for dining quality, both on service and food. I have not had good experiences there.