I'm not sure how DLC will inflict interior decoration on main island as my progress is not substantial yet. However, if we will be invited to our residents house (main island) we may got an option to buy some of furnitures. Today, I asked for a dish I gave for a villager last night and I've been told, as she received for free not asking for any money.
I'm not sure if I understand... at this point, today only food itemt I can get from nooks is a fruit - and this fruit is native one... or maybe you've been thinking about something else?