Coach has a video on setting up his sling that shows the rear attachment point and general setup. You can run the front attachment point near the receiver (I do this and think Shrek typically does as well) or out near the muzzle (his video shows that setup). I think Shrek and others will say personal preference with pros and cons to both arrangements. Here is the link -
I don’t use BUIS amd Shrek does not. I think he recommends offset BUIS if you are going to use them but cannot recall specifically.
Check out his demo videos and some of the coaching videos on this site for examples of front hand placement on the guard. It’s not extended or C-clamped like some advocate. It’s a comfortable middle ground with a cupped hand supporting the rifle.