I'm not 100% sure what you are asking, but I think this is the general area you are after. If not, just say so.
There are indeed two exposures for a flash photo, one the camera makes for the scene (or background) and one the flash makes for the subject (or point of focus). If the flash is set on ETTL, this one will be done automatically. Set your camera up as you would for the background (assuming you are outdoors?) and the flash will take care of the subject so long as that subject is within the flash range. Indoors, I set my camera up like so: 1/125 shutter speed, ISO 100 (or 200), and my aperture at 5.6 or so. Your meter will say HEY! but once the photo is taken the light from the flash will fill in what the meter sees is not there (light). From there, I look at my histogram and adjust accordingly.
As for a chart, Hopefully Curtis will chime in here as he has a great calculator for this and also DOF, but I don't currently know the link. Hope this helped a little.