If you put speakes behind the screen wall, then you should use 3 identical speakers with an accustically transparent screen. Depending on budget, I'd use 3 M80's, or 3 M60's, or 3 M22's. It might be better to use the in-cabinet versions with the ports on the frontsize, because the bass traps may interfere with the rear ports on the other version.
As for subwoofer placement, I'd wait and try it in different places to see where you get the best sound quality. Don't plan on a single placement, because you'll be dissapointed later.
