Well, it seems we can have cows, a dock, bee hives, stables, garden, fish hatchery, greenhouse, and probably some more we may not know about . I wouldn't be surprised if you could have an entire farm.
It would make sense to be able to use the Lumber Mills and Grain Mills for raw materials, like we do with the Firewood for arrows in Dawngaurd. However, I am not sure if I want to saw enough logs to build a house in this game. I kind of want to just go to the Tamriel Depot and order up the lumber and have it delivered.
I've been really hoping for a greater emphasis on food with one of these DLCs. The very term hearth implies food (baking and cooking) just as much as it implies house or home. I would fully expect the grain mill on your property... as well as every other grain mill you find in Skyrim... will be fully usefull with this DLC installed.
Well the vid shows a guy taking bread loaves out of an oven. That's new. Maybe now we can grind wheat for flour and then use the flour to make bread. Course bread has so few real uses in the game, other than just laying on tables everywhere.