1. Each Zelda game stands on its own (except Majora's Mask). Prior experience with or knowledge of Zelda is not required to enjoy any game in the series (except Majora's Mask).
2. The Wii U has access to 9 out of the 17 main entries in the series: Legend of Zelda (NES), Zelda II (NES), Link to the Past (SNES), Ocarina of Time (N64), Majora's Mask (N64), Wind Waker HD (GameCube / Wii U), Minish Cap (GBA), Twilight Princess (Wii), Skyward Sword (Wii). Yes, it is backward compatible with Wii games.
3. The Wii U has many controllers, though your options vary by game. Zelda Wii U will most likely support the Pro Controller as well as the GamePad. But it's not as bad as it looks.
4. 3D games in the series do indeed typically take over 30 hours to complete. If you want something shorter, 2D games (Link to the Past, Minish Cap) fall more into a 10-15 hour range.
