NilesWVC100E Weatherproof Stereo Volume Control with Selectable Impedance Magnification

I know it says 14 gauge, but could I hook 12 gauge up to it? Also, can I hook two speakers up to them? or just one?

Will this mount to a standard 1 gang box? With the 4 screw positions it doesnt look like it will.

Does this come with the outside cover and knob? I would think it does, but it's not in the description or pictures.

Might be a dumb question, but does turning the volume all the way down actually turn off the speaker?