Okay, 1, 2, and 3 are pretty solid, but I'm going to add a few things.
In #1, circling is probable if the 'yote is being lured in, as in someone using a varmint/predator call. If the critter just happens to see a decoy sitting quietly at close range, there's a good chance it will charge right in without circling, so keep that in mind.
For #2, camouflage is worthless unless a person can sit still. A 'yote can detect movement from a long way off, so for best results the hunter has to sit as still as possible, moving only their eyes. Set up your position with this in mind.
Also, add a keen sense of hearing to the coyote's bag of skillz. If that camping chair squeaks ONCE when you shift your weight, every 'yote in the county will be heading the other way -- fast.
I'm not questioning what your girlfriend told you, but I will say that I find it kinda strange that the 'yotes are traveling in large groups. Other than family groups of 4-5, I've never seen a large group traveling/hunting together. Is it possible that these are feral dogs, running free and feeding themselves by hunting? Have any CoyDogs (coyote/dog crossbreeds) been reported in this area? These are the only two things that I can think of that would explain a larger group of canines (no wolves in that area, I assume? ). In all fairness, I have to say I've not hunted Coyotes in the South/East/SouthEast in more than a decade, so things may have changed a bit, but I've never seen groups that large in the Northern-Midwest or North-Central areas.
If you're going to limit your shots to 50 yards or less, have you considered using #1 or #3 buckshot instead of slugs? A swarm of .30 or .22 caliber lead balls might be more effective on moving/multiple targets than a single hunk of lead, and shotgun slugs can bounce/ricochet in unbelievable ways.
Also, make sure any pets (especially dogs) are SECURELY locked-up before the hunt begins, and not released until it's over. I've heard several sad stories about loving-family-pets/guard-dogs running out to join the hunters in the dark, with predictable and sad results.
Hope this was helpful.