Heath, welcome. If you get the items that you suggest, you can be confident that this will change your lifestyle(Lifestyle?)for the better. Unless your room is very big it wouldn't be necessary to go with QS8s or VP150. In fact, with a tight budget you could consider doing without a center speaker temporarily and letting the M22s form a "phantom" center, which they do very well. If a center speaker is used, I'd suggest an M2, positioned vertically, which would match the M22s very well and have wide and smooth horizontal dispersion.
You don't have to be concerned as to whether the speakers have impedances of 8 or 6 ohms. Despite any cautionary language in the manual the 915 can easily handle those impedances at its 8 ohm setting and will give you audibly flawless amplification.
