DG, welcome. The W22s should be very good for rear surrounds. The QS8s provide plenty of dispersion for general ambience and more directional speakers in back would give a more precise location for specific sounds that are meant to be heard in back(although QSs certainly do an adequate job even with those).
As to the center channel speaker, although a VP150 over the screen and pointed down certainly works, my suggestion would be to consider a vertical M60 under the screen if there's enough room or an M22 if there isn't.
