Sorry for the delayed reply. Had to go into work for a few hours. I will try to answer the above questions.
1) Receiver has XT32. But I do not use it. Have tried the calibration twice and did not like how my system sounded afterwards so I just play with speaker placement, crossover point, and trim levels. For me, this is what has worked.
With that said, I will take the above advice and just use a single output from the receiver to the 2x4 and work from there.
2) Those are 21" subs in 6cuft enclosures. Placement becomes limited when adding mini fridges to the room! I used to tuck a pair of 15's behind the front speakers but no luck doing so when I decided to jump in on the 21's.
Subs are 13ft from the MLP. If/when I add the rear subs, they will be right behind my couch. My couch sits about 1.5ft - 2ft feet off the back wall. Enough room for a custom enclosure to house them both. Either dual sealed chambers or a dual opposed setup. As is, the bass performance is already outstanding with the two 21s. They are wired together off a single channel of a plate amp. I am yet to wire in the big amp and 2x4. Why I'm here as the dumb dumb.
3) As far as my front speakers go. 1st, look at the room. Not ideal. A rental. Left side has a corner and a big window, Right side opens up to the dining/kitchen area. There is a fireplace behind the subs/center. lol Work with what I got. As far as the towers. I used to sell Energy speakers. Always loved the Veritas series and have been using them since roughly 2000. Have used them in many configurations. The reason for the smaller V2.3i towers being used as the mains is simply because they are a better imaging speaker. I used the V2.4i (bigger towers) as my mains for several months. They just don't sound as sweet to me. I listen to a lot of music in 2ch so I want the better sounding tower as my mains. Their placement was dialed in for imaging and midbass well before those subs were ever there. I have a 92" screen that sits between them, so I had to play with how far off the wall they sit and the toe in. No measuring devices, just simply what sounds good with my favorite discs. I then built the subs to fit where they sit. Years before, I played one of my 15" subs all across the front to see if there were any poor spots, all sounded fine in the MLP. The left corner obviously bumped up output a bit but it sounded fine across the front. So I was confident the two 21's where they are would be fine. I retire in less than 3 years. Moving out of Cali, buy a house where I can start over with a dedicated room. But for now, here it is. Hopefully that explains why I like the smaller tower better.
As far as the front wides go, I would love to go about 6" wider, but don't think the "left wide" would sound very good on the other side of that wall sitting outside. The "right wide", is actually in the dining area! lol No WAF factor here. Never again. Get my two sons through college, then retire somewhere else. BTW, I do get what you are saying about the wides. But in my system, as it sits, it works. The two wides sit 13.3ft apart. They are waaay outside of the Prime Spot and sit a good 1.5ft outside of the couch ends. The soundstage extends out way wider than they sit sometimes on certain movies. Running the wides also makes the front stage far more powerful and dynamic. I've lived with these speakers for almost 20 years. Several different models and configurations. The center is actually a bookshelf model I split up. The real center does not perform as well so I use a single bookshelf now and it is fantastic. Those 5 speakers are powered by the monster Cinenova Grande amp. Tons of power. I love it. John Wick 2 club scene is insane!
So, while not ideal, it performs. Just need to get the sub situation dialed. Thanks for the advice. Will read the mentioned threads.....AGAIN. Years ago so have lost whatever was retained. Set it up and start running REW. Go from there.