Acoustic Absorption and Soundstage

It's said that moving loudspeakers further into a room provides better soundstage depth.

My question is: If there is acoustic absorption material (e.g., a 4'x8' panel of 4" fibre) immediately behind the speakers, on the front wall, will that affect the soundstage?

Also, I will soon be placing new loudspeakers in the room and am wondering if some toe-in is usually the best position (knowing, of course, that trial and error will tell). I've looked over horizontal off axis measurements of my new speakers and noticed how the SPL fluctuates at high frequencies (e.g., at 15, 30 and 45 degrees off axis - although I'm not experienced enough to know what it all means). Any help in this regard would be appreciated.
Absorptive panels of that large a size directly behind the speakers will have an effect on soundstage. In my experience it resulted in a muted less spacious sound. I found absorption to work best on the back wall. I prefer tube traps for their versatility.

Toe-in is speaker and room dependent. My ESP speakers are designed to fire at 45 degrees into the room and cross axis in front of the listening position. In contrast the N802's are spaced a bit closer together and I set them to aim at the outside of my shoulders at the listening position. This is using the same room but only one speaker pair at a given time.