Yes, the princesses are at all 3 meals - breakfast, lunch, & dinner.
You'll meet Cinderella in the lobby for a meet & greet & photo. If Cinderella is "sick," the Fairy Godmother normally takes her place.
Last September, the princesses that were circulating during our dinner were Ariel, Belle, Sleeping Beauty, & Snow White. However, I've heard that, since Enchanted Tales w/ Belle is now open, Belle no longer appears at CRT. The princess that is normally there now is Jasmine, I believe.