I imagine the confrontation between Kellhus and the Mutilated will be something that people will be parsing for years to come (not unlike the Kellhus & Moenghus showdown in TTT), so you're far from alone.
That being said, the general thought line regarding the "purpose" of the No-God and the Apocalypse and all that goes with it is to "close the world shut from the Outside", the exact particulars of which are still kind of opaque. Nonetheless, it seems to boil down to those who are Damned seeking to escape Damnation.
As for the "artful" comment, I believe this is simply the Mutilated's way of explaining that the method of achieving the above result (closing the World from the Outside and the Gods and all that) is not a matter of complete and total extinction of mankind, but rather the reaching of a very specific number of deaths (or, alternatively, a specific number of people left living, since there are supposed to be some 144,000 individuals that will survive the Apocalypse).
What happens after that I think is very much open to debate I'm afraid. I personally have numerous pet-theories, but my inclination at this particular moment is that by reducing the population of Earwa to the aforementioned number creates a sort of metaphysical paradigm shift, altering the nature of Damnation, the Outside, the Gods, and so forth.
And indeed, the Dunyain (or at least the Mutilated, who've almost certainly been subjected to the Inverse Fire) share many, shall we say, cultural similarities with the Inchoroi and pretty much everyone involved with the Consult.
Lastly, I do not think the Mutilated have abandoned the Absolute -- rather, to them, the No-God actually IS the Absolute. Whether that's true or not is seemingly open for interpretation both for us readers but also for the in-universe characters themselves. I doubt we'll ever get a conclusive "answer" to this since it's kind of intrinsically unanswerable (which is why we humans in the real world have been -- and still are -- debating this idea since, like, forever).
Hopefully that answers some of your questions! You're asking the big ones, so there are many and variegated possible interpretations.
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