Information confirmed here

- download a shopping list from Roxanne (bartender)
- use this list to purchase new items in item shops
- expect rare items, as well as normal items at lower prices
- shop will be updated frequently, with special holiday items included
- playing multiplayer and obtaining a list will result in another unique shopping list
- downloadable quests offered by Square-Enix every week
- quest types: treasure hunting, monster battles, and mini-sub stories
- no word on pricing

Link