Originally Posted by mganapa
[*] Is it better to have rear surrounds (surround back left/right) or front wide left/right or front height left/right?
[*] Should I use a different cable for subwoofer wiring?
I don't understand the first question. A powered subwoofer uses regular RCA cables, versus a passive sub that uses suitably thick lamp cord or Romex etc from the power amp.
[*] All speakers - better to have them 2-3 feet away from the front/rear walls and 1 feet away from the side walls.
The only way to know for sure which distances give the best results is to measure the room's low frequency response at high resolution as you experiment. The ideal
place for loudspeakers is inside the walls, with the front baffle flush with the wall. Most people are unwilling to do that, but the notion that "farther away is always better" is incorrect.
[*] All Speakers - Better to have the tweeters at ear level but if this is at the mid point of the room height then we should either raise or lower this by about a feet.
Tweeters should be at ear height, but woofers should not be. But this is not always a problem, and again measuring is the only way to know for sure.
[*] Front speakers 6 - 10 feet away from each other and in an equilateral triangle from the main listening position. The main listening position would be the center of the front sofa.
In a room that size I think ten feet apart is better than six feet.
[*] Surround (Left/Right) speakers in my case are direct radiating monopole type and it is better to have them either on the side (close to the viewing position) facing the front wall or set back by 2-3 feet angled towards the listening position. These are not the surround back speakers.
It's not so much the distances as the angles. My Room Setup article linked above shows the proper angles. In your case things are confounded by two couches. I have two also, but everything is optimized for the front couch since it's rare to have so many visitors that people sit in the rear. And when that does happen, my wife (bless her) is glad to back sit there so the guests get better sound.
[*] Center speaker is to be placed at the same height as the front speakers in a wide arc to have a smooth listening experience on the front channels.
[*] Based on this placement, Identify the first reflection points for EVERY listening position and use traps at these locations.
Yes and yes.
[*] To achieve all this, it is better to have center and surrounds on a stand rather than a wall mount/shelf arrangement.
Again, what matters most are the angles, though it's best for all five speakers in a 5.1 setup to be the same distance from the prime seat.
I'll let others address your speaker mounting questions.