I wouldn't mind dlc if its clear that the content was developed after the game was done developing. Most Nintendo games this gen have reasonably price dlc so I would expect Zelda U to have the same deal.
As for things in the overworld, i would love to have mini dungeons with useful but not mandatory items inside (bottles, magic rods, multiple heart pieces, crafts for swords and shields, etc.) or fairy fountains that grant new abilities or weapon upgrades either in stock amount or power (bows, rupees, bombs, boomerang damage and speed, etc). Winwaker and Ocarina of Time sort of did this and it was awesome. I rather find useful items in places like that than being awarded with them from tedious mini-games.







