Hi mate, the Canbus friendly type have a resistor attached to the wiring, basically this takes the brunt of the voltage so the HID's don't throw up a warning light. There are mixed reviews about this as it can cause problems with wiper control (on the same circuit) although vRS Carl had this type fitted to the Bullet for more than a year without any problems. I have HID's fitted to the Marauder which are NOT Canbus friendly, to stop them giving a warning light Carl adjusted controller 9 with VCDS to 'xenon's without shutters' he also turned off the cold diagnostic on the side light so I could run LED's without the resistor. I prefer this approach as the Canbus works as it would if factory xenon's were fitted.
As to colour temp, OE is 4300k, Carl had 6000k which I felt were too blue, so I went for 5000k, again imo, the best choice, whiter than OE but with no blue tint!
HTH, Lee.