Question: In the "switches" mission in Agrabah (when you're flying on the magic carpet) what should we do to trigger them?
Question: Where was Kairi all this time?
Answer: Although it remained unclear where Kairi went during the events of Kingdom Hearts 2/Final Mix, it is safe to assume that she stayed on the island until Axel kidnapped her, only to be taken from Axel's hands by Saix. This event was mentioned during the Heartless massacre (inside the portal connecting the "fake" Twilight Town with The World That Never Was), where she ended up meeting Naminé before reuniting with Sora and Riku in that world.
Answer: Lock onto them and look at their color. If they all turn blue cast blizzard. If they all turn red cast fire. If they all turn yellow cast thunder.