1) I could put the surround on the left side of the couch on top of the fireplace which is 59" tall, is that too high?
Not at all. You probably want both surrounds and rears fairly close in height so that panning is even but the QS speakers are very forgiving in placement. Also make sure to leave a few inches for the up and down firing drivers.
2) The pillar on the right side sits just in front of the couch, is that too far forward (i.e., 2-3 feet in front of the listener once the listener is in a lounging position)?
It’s not ideal to have it in front of the listener but if you have no other choice. Also the QS speakers are going to be more forgiving with this sort of placement than towers or bookshelves.
3) Do the left and right surrounds need to be directly across from each other?
Not perfectly but I think they could sound unbalanced it they aren’t. maybe someone who has them like that will comment.
Ideally you want the left and right surrounds at ear level, do you not?
Actually most recommendations are to place them at least slightly above ear level to get wider dispersion and surround effect for HT. For audio having all the tweeters at ear level is probably more important. I found that all my speakers including M80 mains sound better elevated so the tweeters are about a foot above ear level including for audio. Seems to give much better dispersion to all of them.
It there a reason you can’t ceiling mount the surrounds and rears? Many people prefer them mounted higher up. Again the QS speakers are ideal for this.
