@ Charma: at some point of the game you can buy the icecream. I don't remember after which demon though. Just keep coming back and ask.
@Granny: you find the Horizon Island map
and once you have it you must go to that village on the Zander continent, Exelion, and talk to the sailor who used to take you back to Zenna. You can now choose to go to Horizon Island instead.