Use some common sense, though. These are cheap units out of China made by Chinese with no comprehension of the English language. They say BACKSIGHT, but I'm pretty certain they mean BACKLIGHT. There's no other common English word that fights the context.

Someone else told me that Innovatek's manuals are ****, too. And the chopcolate firewall analogy was a damn good one...

My guess is that both those need a 12v line. The backlight might be better suited to an ACC or even the headlight line, so the backlightling comes on when you turn on your lights.
The e-brake wires into your e-brake to prevent you from using the unit unless the e-brake is applied. It's a safety/legal feature. I'm pretty certain it will work just fine (and while driving!) if you don't wire up the e-brake line, although I'm not 100% certain on that.