This bracket allows you to mount a standard cheap servo next to a light switch so that you can control the switch from an Arduino or something. This is nice because it requires no direct interfacing with high-voltage AC, slots onto an existing switch easily, and doesn't prevent manual operation of the switch.

Two variants are included: one with just the bracket, and one with a spot for a 400-point breadboard (or some other electronic thingy) next to it.

See this blog post for details: http://discspace.org/easy-servo-control-of-wall-switch-gives-ac-automation

Doesn't Matter

Yes

Need supports everywhere for the overhang.

See blog post for instructions, the type of servo to use, etc.