Voltage is fine on the stock system, but that's why I said you must disable the DRL resister. If you take that "out of the loop" then you shouldn't have any issues with voltage. However, certainly the "safest" method is to run a relay directly to the battery.No you do not need to unplug the DRL resistor if you are using the relay harness and getting power directly from the battery. That is if you want to keep the DRL function. I have HIDs and DRL with no issue just like Tony.
Not sure what you mean by DRL no longer valid if you go HIDs.
Yes HIDs are not drawing more current than stock halogens, but if the kit is not drawing directly from the battery the ideal voltage for the ballasts may not be achieved (especially with DRL function intact).
DRLs are no longer valid if you don't use a relay setup because leaving the resister in will most likely cause failure with your ballast. I didn't consider that you might want to run you HIDs all the time as your DRLs. That also seems like it also might put premature failure in your future just from lots of extra use. At that point you're not really running "DRLs" anyway though since you're just leaving the headlights on all the time. As far as using the original system as intended by adjusting intensity with a resister.