Actually the SL/SR are hung on the side walls about 12” from the back wall.
Lena,
Your husband is a lucky guy!
As for your future speaker set-up, if you can find a listening position where the 4 surrounds are equidistant (or as close as possible) from the sweet spot, then I think you will be all set. There's no way for the speakers to be time aligned with all the seating positions in the room, but at least there will be that one spot where everything (speaker distances, volume levels, etc) will just SNAP into focus. Great for wowing friends!
And don't worry about the mains and centre, as those can be separately time aligned and level matched on the 950.
_______
Sanjay