Pretty much any random brazier or fire that shouldn't normally do damage unless you happen to be standing on top of it will cause damage from roughly 10 yards, at least... The fires burning near Thrall for example, you will get damage standing almost anywhere in the middle of the hallway at the entrance to his room, should normally only occur if you are right in the fire. Seems like it would be something static that could maybe be toned down in the database somewhere, but I have no idea where to look.
Stealth has never worked that way for me, the best place to test is near Tarren mill, the starving mountain lions are completely invisible, I thought at first it was a level issue but they remained completely stealthed as I went from 21-30, most of them are 23 or 24. I see it also happening on the level 33ish mountain lions above and a few other similar mobs.
I managed to get a half decent Fel Reaver patrol by using .npc add and then manually creating some waypoints for it to follow, it needs some fine tuning so it doesn't bunny hop along the terrain but I can't say I didn't see it happen a few times on regular wow as well