Ask this in a Canon crowd - all their lenses don't have aperture rings, they don't have the luxury of choosing between G or non-G lenses!
1) What you see through the viewfinder corresponds to the current lens' maximum aperture's depth of field.
2) Electronics control the aperture on both G and non G lenses. These electronics have existed on Nikon bodies sold for the past 10-15 years, both film and digital. It can be user selected via control dial. The elctronics also allow far more precise aperture selection, down to 1/3 stop - as opposed to full stops if rotated via manual aperture ring.