1) you can't get more tonal resolution/information or
luminance-range out of a raw by shifting its EV! most cams will capture with 14bit, older or less exp. ones wit 12bit. your monitor won't display this information, so raising ev wont'n bring you some more details out of the shadows, it's already there, but invisible for your eye due the inability of your monitor; 2) 3 stops ...