well, Maybe a question about how Feng Shui affects warp energies, as that seems to not technically be connected to our cultivation specifically...
Here's what we'll do, I'll give you the mechanical answer for the below question and after that tell me if you want me to give you Okertaku answer (which may or may not be different) or pick another answer.
2) When will Kuvara be safe enough from the Chaos Gods? Is there an actual win condition for her, will they give up at some point or can she fortify enough to be able to hold long-term?
This very much depends on what you consider a win condition, it's the sad truth that the warp is the chaos gods domain (as in their territory rather than A D Domain) and most entities that survive in it and aren't aligned with it do it by staying out of sight and being too hard to be worth the effort.
And Kuvara is both in their bullseye and very much not too tough of a nut to crack (and even if she was, they are pissed enough not to care).
So, a "win" condition isn't really the cards, best you could do is keep her alive and occupying attention, one could say that keeping her alive is the win condition but she won't be safe (even relatively) until the chaos gods are on the back foot at least and likely not until they are dead.
Well, that or if something more important came up to pull their attention away.
1) What is the relationship between a god and their domains? We once thought/realized that a god IS their domains in some ways, but there's probably more to it...
"A god is the domain; the domain is the god"
"This is a good enough description of the basics to understand anything else you must know what domains actually are, the basics at least".
"To make a long story short, domains are the manifestations of an ideal concept, from basic things like fire and water and more complicated concepts like home and deceit"
"The warp, a place of thought, intent and concepts, is the easiest place for such forces to manifest in, there are an untold number of domains floating in the warp many claimed, many not"
"A god is the domain; the domain is the god but while every god is a domain not every domain is a god"
"Domains become gods in one of two ways, intent or subsumption"
"Intent has a few forms but the most relevant is faith, belief is powerful and it carries an impression of the one who posses it, and when enough impressions are absorbed into the domain, they grant it a small measure of agency"
"At this point the new god is more like a computer then a true being, as its so beholden to its nature it cannot act against it even if it means death"
"As more faith is gathered, the impressions are absorbed to improve the code (if were continuing the computer metaphor while the power in it is utilized to act as the domain dictates"
"Still very much a computer, if more advanced and able to fake it more"
The second way, is for a being to grasp a domain and be subsumed by it, this happens frequently most mortals can't comprehend a domain let alone bear the wight on their soul, a few manage mostly demons and deva who prepared for it but here and there a being of the real manages it by pure luck, not that its dos them much good, seeing as how they can't manifest it in the real"
"But I digress, the subsumed mind become slaved to the domain and allows it to think and act"
"it's important to note that even this is just a computer able to only comply with its directives"
"Both roads lead to the same point a being who only follows his code, this changes when a god claims his second domain"
"The code of both domains clash (for a lack of a better word) and in the place they clash freedom is afforded and it's here that a gods true personality begins to form"
"There is more too it of course but those are secrets I would not revel"
3) We saw how the Burning Plague was a special disease that violated physics and affect the soul too. What does the "change" we see in the soul of even healed people mean, and is there anything we can do about it? Should we be worried about new variants of this plague just appearing out of nowhere?
"The change you see is the soul gaining an affinity with a domains concept, it is a claim upon the soul it makes it easier to claim the soul and easier to imbued it with power if you wished"
"there's nothing much you can do about it, cutting away can be done but requires that the cut be made with an intent that overpowers the domain the affinity is drawn to, doable for a minor god less so for one of the four"
"I know of methods use to cleanse this taint but nothing specific"
"you should likely worry about random plagues appearing giving who were dealing with here but not from this, besides everyone has some affinity with the disease domain, this just strengthens it"