As for Rose and Miles, I think the scene was merely just to flesh out their personalities more. In the prior episode Rose interacts with Charlotte and says "Watch your tone, Red!". In this episode she interacts with Miles and says "I'm keeping my eye on you, shorty!". They're just giving Rose more time on screen (thank god!).
Besides, I doubt Rose was worrying too much about food considering that they all know now that there are homes with electricity and refridgerators on the island, as well as nobody has even come close to starving to death while there lol. Plus, Rose knows the island heals (at least those it wants to heal, anyway). She probably would not be saying "The island cured my cancer. But will it will also let me starve to death. We better hoard those peanuts."
