The standard ascended are those do-nothing chumps in the diner. They have a policy of non-inteference.
The Ori and the ascended got into a fight, and they got kicked way out to another galaxy, while the diner assholes took up shop in the Milky Way Galaxy.
Interestingly enough, the Ori grew themselves a community of humans, so we really are cattle to overlord aliens.
They call their galaxy "The Ori Galaxy" Very creative. I don't think we ever see star charts, we're just told they're super far away.
The scarification is individual, and sort of a show of rank, much like the tattoos of the Jaffa.
There is a DOCI on the planet Celestis, he's kind of the evil pope of the Ori. Not sure on the fire thing. I vaguely think they like it for it's cleansing nature, which is some pretty unfriendly doctrine.
The door knockers are called Priors, and their level of cruelty is directly tied to resistance.
I know it's ancient history at this point, but SG-1 are banned from the in town steakhouse in Colorado Springs. They behaved poorly while under the influence of alien wrist bands.
I don't know if it would really be fun to hang out with Jack, he's kind of an bottom to anyone he doesn't have an established relationship with, he even dumped his clone off at a high school and never checked up on him. Teal'c did not enjoy being a house guest with him, but would obviously put his life on the line to save his friend. So that's interesting.
Meanwhile, if you're in the hospital with brain shrapnel, Mitchell will bring Pizza, Beer, and a playstation! And if it turns out it's terminal, he'll let you live out his space adventures.
I think it was established the the friend with brain shrapnel was up for Mitchell's first job with the SGC, as a space fighter pilot. He's... actually pretty good at that job. Got the MOH for it.
It is frustrating that there are some extremely rich moments in S9, but the Ori just flat out suck.