Speaker placement varies with every speaker system, there are no standards to really follow. You can check out the Cardas website, you will find their system for speaker placement in a room based on the room dimensions which is a good starting point. You can also try the rule of thirds for placing speakers, a third of the way into the room from the front wall and a third into the room from the side walls. Start their and move incrementally forward and back, side to side until a familiar recording locks in place. You will know when it happens. It might take many tries to find the right spot but you will be happy that you went through the trouble.
Why does pulling out main speakers from wall improve sound?
Ask my dealer this question and he was stumped. He said it's a good idea but couldn't say why. I see speakers pulled out eight or more feet from the wall in very nice systems.
The drivers are facing forward, and when there are no ports in the back of the speaker so why would it matter?