Battery info: batteryuniversity.com/learn/article/whats_the_best_battery

Regulator info: components.about.com/od/Components/a/Types-Of-Voltage-Regulators.htm

I hope this tutorial was helpful, and that you are more educated on the different types of power supplies, batteries, and regulators. When in doubt, ask on the Ez-robot forum. Anyone is a source of help.