Setting the idles and fuel/air ratio

I don't think you would get a different answer on the fuel air ratio with or without the headlights. If you need to speed up the idle a tad to compensate for the headlight drag, go for it. I don't think you need to readjust the mixture, just increase the idle speed. Also don't get too hung up on the numbers. As long as it idles good for you and doesn't want to creep too much while idling in drive (assuming automatic), you should be fine.