[woode]

The answer to all three of your questions is you should run a relay when adding lights, or anything really for that matter, and not just tap directly into the source.
Better yet would be to run a relay and a fog light switch instead of them being switched on by the headlights because why would you have your fog lights turn on at the same time as your headlights? Fog lights are for when it's foggy out.. *Edit: nevermind, you're going for the ricey blue lights everywhere look.. just add a relay and you won't have anything to worry about. Especially if going with HID otherwise you will be blowing fuses and/or melting wires eventually.