Elka has one of the pymaric simulcrums.The one she's looking at in the last panel we see her with the catalogue. She appears to be looking at her hand in that panel, as if she's comparing it to the one in the catalogue, and if you look closely, it looks like her palm is glowing blue, just like a pymaric. It could just be the lighting, though. Of course, this means that simulcrums must be capable of looking like ordinary limbs, but surely, in a world with healing magic, it would be easy to graft skin over the metal or some such thing? Either that, or she's thinking about getting one.
The real reason for Sette's mission is to get Duane into CresceLord Winalils mentions the Ilganyag, so he is almost certainly a member of the Black Tongues. He also looks similar to the Black-Tongue doctor that Cara describes. He probably convinced Sette's father to send Sette to Cresce with Duane. They used Sette because they knew that Duane felt protective of children. And apparently Starfish is being threatened by Frummagem to get his job done. Matty suggests that Starfish is smuggling something that likes pain, but maybe he is actually luring Duane by hurting children (although there seem to be some magical reasons as well).
The crow amulet Bastion gave Sette is Duane's phylactery.Think about it: Duane is really closer to a lich (albeit a primarily benevolent, involuntary one) than a typical zombie, and clearly has his sense of self/soul harbored elsewhere considering that his brain dribbled out his nose years ago. The amulet gives Sette control over Duane in the night-time hours, and also bares a crow motif- very similar to the crow deity that serves as a 'mascot' for the Black-Tongues. At very least, it's filled with his blood from the night he died.
Sette and Duane are Decoy Protagonists. The real story is going to revolve around Murkoph.Ashley pretty much says it outright here.
Murkoph's body is made out of First Materials.Murkoph is a roleplaying character of Ashley's who will be appearing in the story eventually. He's apparently a zombie who has maintained sentience, like Duane. We don't know much about him other than that — all we have to go on is a short comic on Ashley's deviantArt page. That comic (assuming it's canon) is pretty enlightening, though. In it, not only is Murkoph surprisingly well-preserved (unlike Duane, who is a skeleton), he's standing over water. Pymary doesn't work over water, and since zombies are held together purely through pymary, they just collapse if they go over water. But Murkoph is just fine. The only things that can maintain magical properties over water are enchanted First Materials, so it's probable Murkoph made a body for himself out of some. (This would also explain why he doesn't decay, since the enchantment preserving him would be permanent.)
Duane will become Murkoph.Murkoph is very similar to Duane — a plod that has maintained sentience. He also likes to ramble a lot about existential weirdness, something that isn't entirely uncharacteristic of Duane. Murk's psychopathy should disqualify him, but Duane is already displaying Sanity Slippage...if he snaps, Murkoph could be what he becomes. Furthermore, assuming the above-mentioned comic is canon, he's a tacit caster as well...
Quigley is doomed.Even setting aside the fact that he's entering the threshold for keeling over from old age at any moment, he can't stay alive if the plot is to be kept intact. Quigley wants to save the children from Starfish's operation, which will derail that major plot thread. It's too early for that plot to be solved, even partially. There's also another problem that decreases his survivability: whatever wants those slaves isn't going to be happy if Quigley comes up and goes "So hey I'm taking these kids with me bye~", especially if they're the main course. As if that wasn't enough, Ashley says there's going to be a Wizard Duel in the next chapter — almost certainly between Quigley and Duane, which would be a perfect chance to off him. As a corollary to this, Matty may be doomed as well without his father to help him...
Bastion had something to do with Duane's reanimation.We haven't seen much of Bastion so far — however, in the one scene we've seen him in so far, he places great emphasis on Duane's condition, insinuating that calling him a mere plod is not at all accurate. Alone, this wouldn't be too suspicious...except that Ashley has also said on her Formspring that he's an exceptionally knowledgeable gruftgrammer who knows a lot of weird, unknown magic. Most notably, he's practically the only wright on the continent who can reliably teleport, a skill that requires a strong sense of self. Duane's enchantment seems to use a similar function — his self is persisting even after his death. These facts seem to point to one of two things: Either Bastion reanimated Duane himself, or knows a great deal about how he was reanimated.
The reason pymary fails over large expanses of water is because...(Post your own theories here!)
In life, Duane was a GoldThe girl Duane sees in flashbacks has blond hair and green eyes, and it might explain why Duane can tacit-cast since the Golds have an odd connection to the Khert. And when Quigley asks him his caste, he replies ssom soud, and according to the wiki "soud" is the name for the Gold caste. I'll actually be surprised if this isn't the case.
Sette is connected to Tirna in some wayMostly based on her command over insects, which are shown to be associated with Tirna. Her independence, her by turns vicious and loving nature, and her understanding of the world are also thematic links. Could be an actual in-universe connection or simply a deliberate allegorical link to add a layer to characterisation.
Ashley's "tomorrow Matty dies" jokes are actually a cunning ploy to throw us off our guard.At one point, she will actually tell the truth — a spoiler hidden in plain sight. However, we won't suspect anything because of all the other times she's said it. Thus it will be a shocking plot twist when Matty actually does die, despite the fact she spoiled it in advance! (Indeed, it will actually make it more surprising, since we will assume she's lying!)
Mr. Starfish is related (by blood or marriage) to the Frummagems.We already know he's working with them in some capacity, and not just with Sette's branch of the family. Also, compare his face to Knock-Me-Down's: They're eerily similar, especially the nose.
Lawrence Murkoph is Blondo Mcwhoopass from 1-16.Blondo is blond, and Murkoph is... kinda blondish. They have the same general hair/face shape. And Ashley has been sort of ambiguous about whether Murkoph is from Sharteshane or Alderode, possibly to throw us off the scent? And she hinted that someone's theory about Murkoph being Duane's brother might be on the right track.
Murkoph is Ssael.YOU KNOW IT'S TRUE
Mikaila is responsible for Duane's zombie state.From one of the comments: "All this time, I've been presuming that Duane zombified himself to protect his daughter. Now I realize I may have been terribly wrong. It's looking like his daughter did it, as/after he is dying. (Since she now has a displayed pattern of miscasting spells) She must have either botched a healing spell to make him undead, or botched the zombie spell, to tie in his actual spirit instead of just the body, which is the proper(?) way to do it."
Mikaila is alive in the present day.I can see Duane still being in full patriot mode even if Alderode killed him, but I don't think the same would be true if they killed his family. Furthermore, if Mikaila died, wouldn't Duane be flashing back to her bloody corpse instead of seeing her alive and well? He is clearly not a happy individual, you'd think he would be fixating on that if Mikaila's dead.
Sette is somehow born of the Khert.When she's running around in the Khert in chapter seven, she mentions it smells familiar, can interact with it in unexpected ways, and has an odd interest in Lady Ilganyag's 'baby forest.' Duane translates Ilganyag's line there as "Run away," but could be that he was getting the account secondhand, and it was "Runaway"—tl;dr Sette is one of the crow-lady's babies, incarnated in the real world.