Depends on how strong Imperisal influence was in Skyrim before the civil war.
If it was low, KOTN should not be present as they have no ways of establishing themselves there
If Imperial Influence was not THAT low, they should be there. Since 200 years have passed since their restoration, they do not need to be good guys (hell, you can even make them villains). However, they should be mostly present in Empire controlled territories then
Of course, if they are in it would be good to have some kind of a counterweight for Nord sympathizers, like a faction that is created to fight against KOTN's assimilation attempts.
IMO, that would deepen the Imperial Vs. Nord element of the game and the more conflict between those two groups, the better IMO.
The Nights of the Nine was stupid. I hate it whenever they reference Christan crusaders. Guess what, it's TES, Jesus doesn't exist in the game, the term crusade means "Christ's aid". Therefore if Jesus doesn't exist in the lore the word crusader shouldn't be part of the lore. Nor should there be Catholic style churches or Christan style rituals. Edit: or monks.
A lot of TES is based on something from real world. Hell, Skyrim is based on Scandianvia and Vikings. It is many years too late to complain about similarities with real world
That is also true. You really can't call the Knights of the Nine an expansion pack. There just wasn't really much you could do.
That was a DLC, not an expansion. The only ones who called it an expansion were some idiotic reviewers who didn't care to get their facts right and thus spread misinformation. Hell, one of developers practically yelled at an interviewer because the interviewer called upcoming KOTN an expansion ^_^;