You're thinking of the Demons in Tynerum, they were effectively the same species as Demon Slayer and Mastema. As far as I'm aware, their storyline was dropped when Tynerum was removed and Gollux was switched to Phantom Forest. Even before that, Tynerum's castle area was entirely separate and had nothing to do with Masteria
Masteria sunk before the game's current timeline. You can see it happen in Masteria Through Time.
The aliens in Stellar Detectives are just pirates, although they are after the Antellion MacGuffin like everyone else I think. The storyline you played as a merc was Captain Vaga, which was dropped due to technical limitations I believe? The aliens in Masteria aren't PULSAR that I'm aware of, but they are related to Jett.
Aliens invaded, it was a large-scale event storyline in 2012 or so. But since the area was overhauled it's irrelevant.
The level 170 quest "Street Sweeping" and related quests are how you get to know Lita Lawless, as far as I'm aware.
The NPCs follow the questline as if you completed the earlier level quests, as far as I know there's no variation in dialog if you haven't done the earlier quests.
The original Masteria was largely wiped with the overhaul to the area. The only thing that remained are the NPCs themselves, a few asset designs, and certain plot points, much of which has been retooled into the larger plotline.
All classes tie in to the Black Mage storyline at least by Arcane River, at which point the storylines are identical except for some unique dialog for specific characters in specific circumstances.
Adele specifically has certain interactions with other Nova classes (Illium, Ark, Cadena, etc), but to my knowledge does not interact with the Black Mage specifically until level 200. I would have to review my story screenshots to be absolutely certain.
The story is described in the Grand Atheneum chapter 1, in parts of the Tenebris storyline (245+), and in the first part of the Cernium storyline (to be implemented some time in the future).
He felt angered by the fact that Transcendents were actually limiters to hold back the power of the old gods and make fate more predictable, so he rebelled, and banked on his own destruction at the hands of the Adversary. With the Transcendents either killed or weakened, the world is free to choose its own destiny, and the old gods are gaining more power.
Referring to the minimum requirements, a character must be at least level 101 to participate. Because Zero characters start at level 100 initially, Zero characters must be at least into chapter 2 of their storyline to participate.
If you are not a Zero, it's irrelevant; you only need to be level 101 or higher.