Region lock is a no-brainer since their consoles are and their latest handhelds are too.
Backward compatibility was confirmed at E3. Same way (so far) as the Wii handles GameCube's: it turns into a Wii and there. No 1080p, just a Wii inside a Wii U.
Actually I'd argue that the opposite is more likely. In order to hardware emulate the Wii, the Wii U would need to have Hollywood embedded into it. On top of that, a hardware sandbox mode would mean, that whilst running Wii code, the system would only be as secure as the Wii was, making the system much easier to hack.
Chances are the Wii U will do what the 3DS does and use partial software emulation. Since there won't be any hardware incompatibilities, it'll actually be fairly cheap to run and should have 100% compatibility. On top of that it allows Nintendo to run extra software and hardware in the background, such as additional security features or CC emulation on the Umote.
That being said, even with software emulation, Nintendo will be aiming for 100% compatibility as cheaply as possible. That means 1:1 emulation without any, potential glitch inducing, hacks such as higher resolution rendering. Nintendo isn't going to spend thousands of hours optimising the emulator for every single game the same way the dolphin community has.