Dark Souls/Headscratchers

Would the Dark Lord ending truly create the Age of Humans?
If the introduction is anything more than Gwyn's 'Official History' (the existence of the Everlasting whelp and the Archtrees is evidence that it is), the world originally belonged not to the Darkness but to the Stone Dragons and 'humans' were scraggly... things until four of them managed to grab the Souls of Lords (from where is not explained either). The condition of humans at the beginning of the game proper is partly a product of the Age of Fire and any magical effects thereof, so once the Souls of Lords and the First Flame are extinguished the result should be an Age of Undead rather than an age of Humans -- unless there's some unrevealed original source of Humanity besides other humans and monsters (which as one WMG suggest may have gotten it from human victims).
 * All Souls came from the First Flame, including the Lord Souls.
 * Speculation points towards humanity being fragments of the Dark Soul that all humans are born with. Word of God hints toward this being the case as well.
 * The Dark Soul doesn't appear to be dependent on the first flame.
 * Regarding the Age of Darkness, there really is absolutely no telling what will happen to the world when the First Flame dies.

What is up with Frampt, Kaathe and the Primordial Serpents in general?
They seem important, and claim to be as old as the other major players, yet I have seen nothing about them in any of the game's flavor text.
 * This troper speculates that the Primordial Serpents may in fact be the servants/friends/comrades/lieutenant of the Furtive Pygmy, with their powers and appearances strongly linked to the Dark Soul. Even after the Pygmy's death/disappearance, they still remain loyal to him and his cause, and effectively consider the Player Character to be his successor when they proclaim "Our lord had return'st" in the Dark Lord ending. Frampt is the outsider among them, possibly due to forming a friendship with Gwyn and/or Gwyndolin, and turning against his original purpose to instead support the Age of Fire.

What exactly do souls do in Dark Souls?
Souls are described as being the currency of choice in Lordran, while coins are in general useless, but why exactly is this? Souls were traded in Demon's Souls because they allowed a mortal in Boletaria to remain sane (to some degree) in the wake of the soul-devouring demons, but no such justification seems to exist here. Do they have a similar function in preventing the Undead from turning hollow? Is it because the Lords took to trading souls between themselves for goods and services (which would have some dark connotations), and they thus became became the official "minted" currency? Do souls act as a kind of Applied Phlebotinum in the use spellmaking, smithing, and crafting? Or what?

Is it really all lies?
After my first playthrough on Dark Souls, I checked everything about it and how the "To Link the Fire" ending was apparently me being tricked into becoming a willing sacrifice.

But playing the game for a second time, I've come to wonder: Is this assumption really real? I'm listening carefully to everything that Frampt and Gwynevere (or Gwyndolin) have to say, and I'm finding no lie whatsoever in their words. Sure, they tells me I must success Lord Gwyn, but it's NEVER stated this is about succedding him as ruler. If anything, if one knows of Gwyn's fate when he linked the fire, one should know best when you're told to inherit the flame AND to link the fire. In this playthrough, I'm getting the impression that Frampt is telling me - even if not in detail - that becoming this sacrifice is my destiny, and that my character is walking willingly towards this for the sake of the world.

So, is the player really being tricked? Or just deluded by missasumptions?

So, even further plotholes...
Everyone in the fandom seems to assume that Gwynevere is an ilussion cast by Gwyndolin due to the information given in some items.

But then... how exactly can anyone explain that she's still there and gives you all the information she usually offers, AFTER you've killed Gwyndolin?
 * The illusion obviously has some sort of autonomy, like a prerecorded message or something similar.