Hi Ed,
Not that I think it matters in this application but if you're going to use different gauge wire use the heavier gauge wire for the ground bus and the thinner for the power bus. The connection from the IC to the GND will be kept short, the connection from the IC to the power rail perhaps a little longer. The capacitor should be placed across the power supply pins of the IC and its purpose is to act as a local "power reservoir" for the IC as well filtering noise on the supply rail, bypassing it "down" to GND.

It's very important but really not that complicated for the general stuff we're tinkering with.

Here's a link to an article describing and showing how and why and here's a more technical app note from Analog Devices.

/Henrik.