Nancy, welcome. Just to answer one of your questions, the two speakers more toward the rear are commonly referred to as "side surrounds" and are to be placed directly to the side of the listening position or maybe a couple feet father back. Since the couch is close to the back wall that would satisfy the requirement that those speakers not be too far behind the listeners. They should still be well to the side, since they still play side surround sound even though they're on the back wall, and four feet outside each end of the couch sounds sufficient.
