Wiring up multiple gauges...few questions

[beetlejuice]

I'm wiring up 5 STRi gauges into my s13.

1) Where would be the best place to tap into for a switched 12v?

2) Where would be the best place to tap into for a dimmer switch (when lights come on, STRi gauges dim)?

3) Can I tie all of the wires (say, 12v switched) together from the gauges into a larger gauge wire, then tap into the appropriate spot? Or will this somehow negatively affect the gauges?

Trying not to overload any one electrical component by adding the gauges.

Thanks in advance.