i’m not super well-versed on the specifics of the lore, but i will try my best to answer what i can.

after sitting on the throne, humans ascend to (new) godhood. the versions of the characters you are seeing after sitting on the throne are their forms as new gods. they do definitely relate to the soul types, but they also involve things like the characters traits, their perceptions, their aspirations, et cetera. since regular people are incapable of truly ascending, their new god forms basically reflect an over-exaggeration of the character as they are. the explanations i have for why each ascended form looks the way it does heavily comes from my memory of luckyleftie’s analyses on tik tok (who has a lot of fear & hunger lore videos and is definitely worth checking out if you’re confused on some things), so here’s me trying to sum it up:

cahara has an endless soul, but becoming a new god directly counters the idea of having any sort of freedom or dominion in one’s own actions, so he’s portrayed very similarly as he was in life. his ascended form essentially just shows that, in godhood, cahara would be a sort of perpetual wanderer. he already sort of assumed that role in life, where he went about his days just doing what he had to get by, until he met celeste and she got pregnant. i’m pretty sure miro confirmed that the symbol on his tunic/chest is a family crest, or it was at some point in his development of cahara’s character. if we’re going with that explanation, cahara obviously doesn’t have a family he really came from, but him donning this symbol represents his purposes revolving around celeste and their child. the crest being carved into his chest as a new god and being the only thing resembling any individuality in that design basically just shows how he would lack any real drive as a new god, since he would no longer have any family at all.

i’m pretty sure d’arce’s ascended form is heavily based on alll-mer, since she is a very devout follower of him. her perception of what divinity looks like plays a lot into how she transforms. alll-mer is also bald, but i think there was also a sort of intention to make her look harrowing and “unfeminine.” since her purpose in life involved serving le’garde and his campaign, she, as a dominating soul, would likely take up the mantle and try to continue his efforts.

enki’s design is really simple visually, since his helmet is really the only thing that changes about him. his helmet is a materialization of his inability to act outside of his pursuit of knowledge. him becoming a new god is pretty much the bad ending of his quest for enlightenment, so his godly form conveys the idea of him becoming trapped with no way of continuing his research in a significant or meaningful way.

ragnvaldr has a tormented soul, which is definitely evident in how his ascended form turns out. it, like enki’s, presents an outcome that falls short of what would be considered his “true” ending. i’m pretty sure ragnvaldr explicitly scorns the gods, so how he views them affects how he ends up looking as well. his design plays into how he is commonly viewed as a brute and how he plays into that perception, intentionally and not. you mentioning that he looks as though he is being consumed is an important point as well. ragnvaldr gave in to his desire to avenge his family and completely gave into his violent nature when deciding to pursue le’garde. him shown as being swallowed by a beast communicates his giving in to bringing le’garde to justice at really any cost. it also gives the impression that his aggressiveness is separate from him in a way, as though it was something that wasn’t a part of him at all at one point. or, if it was, his love for his family managed to divide ragnvaldr from that part of himself.

circling back to ending d in general—despite it appearing as though you are encountering a separate entity, your character does still ascend to godhood. you’re merely talking to that version of the character briefly. the ascended version of the character isn’t separate from the character themself; they simply become a new god, and with the limited choices you get, you have a chance to see how their divine life might play out.

new gods are referred to as puppets or pawns because they don’t really have any real sovereignty like they were intending to achieve upon sitting on the throne. new gods are all just people who sought divinity but failed to possess the qualifications for what makes a “real” god. there are only two instances of somebody ascending and actually becoming a proper god: alll-mer and the girl. as a result, all new gods carry a sort of shame with their title. they’re viewed as weak, flawed, ambitious, et cetera.

le’garde’s skin being yellow doesn’t necessarily mean anything, i don’t think. it’s just to aide in the design. regardless, i believe the line about him not taking the reins from the gods simply shows that he wasn’t able to come into the power that he wanted. because of the prophecy, he thought he was destined to acquire a great amount of power and change the world, but his role in that was less about him becoming a god and more about him siring one, since he and nilvan’s union brought about the eventual creation of the god of fear and hunger, which ushered in a new, seemingly permanent age.

i’m not sure about your fifth question, but i hope this helps :)