First I' d like to say, great scouting job. Doesn' t sound like you accidentally came up on them and spooked them. Second of all, because of location of beds in this basin and near wallows and all, I' m pretty confident you' re not in their bedroom. This is an area that elk feed water and wallow in like mid Aug. to anytime in Sept.
Elk will frequent these areas midday and evening. once there in the evening they' ll usually hang out there all night, feeding watering and resting, hence the beds. Come daylight or soon after they head off to their bedding areas normally higher in elevation in dark cool timbered areas. If lots of insects out they may seek out benchy areas in the burn on windy points to keep the bothersome insects away. All the trails coming into this basin you mentioned are obviously coming from their actual bedding areas to feed and water.
Your buddy sounds like a smart feller, a ground blind or treestand near the wallows or where these trails intersect into the meadow is a wise choice. You' d do best if bowhunting, which I believe you are, to sit this stand from 11:00 to 3:00 and the last 2-1/2 hrs of daylight. This should be the most active time in the meadow.--- If you decide to hunt these elk at first daylight you will catch them in the meadow somewhere, so be alert, this could be a great time for your favorite sexy cow call.

P.S. Those are excellent questions. hope this helps and Good Luck! elknut1