In general, sit in your favorite spot. Look over each shoulder at the side walls, that is the best placement. In other words, just slightly back from 90°. Wall mount v.s. stands and height depends on the speaker.
If you put the back speakers right in the corners you will have the same bass issues that you would have with putting front speakers in the corners. In my room, I put them out from the back and side walls the same as the fronts to start with. Then moved them about a foot wider.
If you put the back speakers right in the corners you will have the same bass issues that you would have with putting front speakers in the corners. In my room, I put them out from the back and side walls the same as the fronts to start with. Then moved them about a foot wider.