Illuminations can really only be seen from inside Epcot. Much of the show is just over the water. A small part of the show is actually fireworks. I'm not sure how much of those you can see from CBR. I'm sure someone else can give you those details.
You can, indeed, see some of Illuminations from several places at the CBR. We have found that the best view is right outside Old Port Royale. Pick an umbrella table near the marina entrance. You can see the EPCOT Spaceship Earth (now with a semi-deconstructed arm and wand) illuminated at night.
We have also watched the fireworks from the Jamaica beach.