I wouldn't recommend it. It's more for surround sound

I don't think so. The rear speakers are very discreet. They're there to provide immersive sound. However, they can be controlled separately via Smarthings.

Yes, it can be used as a multiroom.

No.

I don't think so. The rear speakers are primarily used for surround sound and, as far as I know, cannot be controlled separately (as independent speakers).