Here’s more in-depth answers I was provided with, since the ones in the MMO-Champion post are very heavily condensed:
Q: Did the Arbiter ever send anyone directly to the Maw?
A: In the times before, when the Arbiter functioned as intended, she would occasionally send those souls judged to be irredeemable directly to the Maw. […] Butvastly, it was most people going other afterlives.
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Q: Does the Drust threat in Ardenweald predate the Drust we faced in BFA? If so, how old is the Drust as an entity?
A: The Drust were a people that were alive at one time on the place that would be Kul Tiras, but it’s that that darkness they tapped into, that death-centered form of druidism, that at the time of BFA, that was a novel thing because druidism was traditionally tied to the powers of life and the Emerald Dream. Ardenweald was a natural place to explore that story further. […] We learned that druidism is about more than just life and growth but about that cycle between life and death. The Drust went heavily into the dark aspects of that. […] The idea that Thros was a realm not quite in the Shadowlands but was one certainly touched by it was an interesting story to tap into.
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Q: Will we learn of any specific or force from Thros? Was there a higher being Gorak Tul reached out to?
A: There was no other Eternal One that he was specifically tapping into. It was them tapping into that force with such intensity that made Thros teeter on the brink there, and there’s overtones of the Nightmare as well, which is another variation of that cycle and balance when the Void touched a version of that. Thros was kind of on the precipice of a lot of those confluences.
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Q: Do victims of Necromancy retain any memories from their time in the Shadowlands? What about old memories they may have cast aside after their death? (Example given: Ascended Kyrian)
A: Coming back to life via necromancy is like a mirror to the natural way of things, where a soul is born, it builds up anima, etc. And normally it’s the power of life that binds the soul to that body, and necromancy is when the power of death is doing that. […] This is kind of ephemeral, the way I think of it is even if that soul is pulled back, and it kind of forgets what happened to it over the course of the Shadowlands, it’s still kinda got that tether to what’s going on to its existence in the Shadowlands. Since time is not really a factor there, you can think of it as almost a second life or continuation with the Shadowlands side almost “on pause” or waiting for that tether to reconnect them to that fate. […] Undeath is a very small thing on a cosmic scale, despite how much we see of it on Azeroth with the Forsaken and Scourge, the vast majority of souls who pass through go to the Shadowlands and stay there. […] It’s an interesting question as to whether this might affect their judgment in the Shadowlands.
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Q: What happens when a fresh soul arrives in Maldraxxus? How can they get a body? Do they choose one?
A: The way it was supposed to work, it was still souls coming into that arena that you see, and Margraves would see what they had to offer and say, “I like that one. It should come to my house” and maybe they might argue over which house it goes to, and the Primus could go, “Alright, that one goes here, that one goes there.” […] Maldraxxus is very much a meritocracy. Your achievements in life were kind of the bar to entry, but now it’s like starting a new job where you’re starting fresh and have to prove yourself again, today and every day. You can imagine someone arriving and being given a very basic form they can inhabit, and based on their victories, getting upgrades or downgrades to that body. Where there’s people like Vashj and Draka who climbed the ladder very quickly, they were in a position to say, “I’m going to start shaping my flesh this way”. If you’re successful, you’re given some latitude to decide.
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Q: Teaser for the upcoming book, Grimoire of the Shadowlands?
A: It’s written from the perspective of a broker, writing it for his cartel, talking about things ranging from Azerothian funeral rites, to the influence mortals have had on the Shadowlands, and his perspective on the various realms of death and the events that have unfolded. He makes note of how people from this Azeroth world keep coming up time and again despite all these other worlds existing. There is a chapter in the end that delves into the mysteries of the universe and the nature of the First Ones, and talks about the Broker’s efforts to uncover those secrets. He presents another perspective into their views on the cosmology.
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Q: How does the Eredar & Draenei soul magic effect the Shadowlands? (i.e. Auchindoun) Were they circumventing the fate of souls?
A: With the Kyrian watchers who decide when a soul is ready to go to the Shadowlands, one of the factors is “is there some force that is tethering them to the mortal plane” or some force that is interfering with the process of this. [Example given: Naaru intervening to save Bridenbrad’s soul to spare him from undeath.] […] Those races don’t really think of it in terms of, “I’m stopping these Kyrian Watchers from claiming a soul” so much as they just see things from their own perspective, keeping those souls from passing on, tying them to devices, etc.
Q: Regarding Portals in Stormwind/Orgrimmar - Can anyone just travel into the Shadowlands? Can denizens of the Shadowlands travel to Azeroth?
A: We always put portals by necessity for gameplay reasons, but by and large, those portals are meant to be a gameplay device. But some characters, like Griftah, have crossed over, but think of the fiction there as they would’ve had to gone to some trouble to make that happen. Like they would have had to talk to the Death Knights, or maybe some particular mages who would’ve figured things out based on what Jaina has been doing, just to get the help to open a portal to that place. […] We don’t need to narrativize every bit of that, but there is a barrier to entry. On the other side, beings that are bound to the cosmic realms cannot, just on a whim, come through. Once you are bound to those realms, it takes a concerted effort to cross through. That’s why things like with Legion invasions it’s not just been, “Let’s hop on the bus and head over there” it’s “How do we get the gateways open? We need to use the well of eternity or this temple to Elune because it’s attuned to the Avatar of Sargeras, etc”
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Q: What is the gem used to forge Kingsmourne?
A: That was something Sylvanas hadn’t seen before, so without getting too spoilery, it seems the Jailer has his own stock of powerful things whether those or souls or other forms of power, but it’s also safe to say, that as deliberate as the Jailer is, he didn’t choose something at random. He chose a very specific thing to put into that sword. We will revisit that story as it continues to develop.