I think there has been some talk about Nic; and by extension Anduriel, wanting to defeat the Outsiders, but do so in a way that probably wipes out most of humanity.  I could see the Red Court; if they were still around, not being very happy to see most of their food source disappear, but if Nic's plan involves the use of the Holly Grail or other items that were in Hades vault, I don't understand how the Red Court could get in Nic's way.

Perhaps something as simple as that their large, organized and powerful nation was a junior ally / effective proxy of the Outsiders?

Probably not a coincidence that as the Fomor stepped up into their niche, they were also trying to interfere in Nic's plan to go after the armory.

House Raith is led by female Whamps putting it at a disadvantage against the other houses, and leaving is vulnerable to take over by secondary lines like the cousins.

I'm not convinced Whamps subscribe to human notions of sexism, that having female leadership would be a disadvantage. The Malvora's were led by a woman until the coup attempt, and she was considered just as much of a threat to overthrow House Raith if Lord Raith's weakness became public as the Skavis kird was.  And the coup attempt killed not just the pair of them, but most of the second tier around them.

Lara is probably in more danger from other Raiths when the charade of her father being functional eventually fails than Raith overall is from any of the other houses. She's probably planning as much for that contingency as for external events in seeking the arranged marriage, whether it produces a child or not.

I just reread that scene, Mab's reaction was approval of Harry humbling Marcone in front of everyone, because it was with a sarcastic tone that he called him, "Sir."  Mab was clearly supporting Harry all through that though she didn't say much, she didn't have to, but she seemed to enjoy Harry getting the best of Marcone.

I was thinking of:

Mab's eyebrow went up so far that it threatened the line of her skull. Then she said, as if to Marcone, "Much is explained."

She was backing Harry about claiming the castle because, as she pointed out later, sowing doubt about the whereabouts of the Eye even though everyone thinks he /probably/ has it is even better than advertising it.

But I don't think her reaction to the hint about Marcone holding Namshiel's coin reads as feigned. What purpose would faking it serve? She may have suspected, but this landed as confirmation for her.

I also believe that the island had been without a Warden for some time, the Merlin, if no one else should have known that.

That's also a good point. One of the more knowledgeable characters (Vadderung, I think?) at one point equated a Warden being active to the island being 'awake'.

I have some doubts Alfred, if awake, would have tolerated the Denarians doing a major working on the island's surface. If LaFortier was the Warden and left the defenses sufficiently down to allow them to do that, he wasn't much of a caretaker. Although, Alfred also took some years before introducing Harry to the actual capability to leave defenses turned on, so who knows?

We learned that Kemmler had something to do with starting both WWI and WWII.

Wasn't that part mentioned previously?

But some time (not too long before the start of Dead Beat) Future!Harry took down Real!Cowl, and replaced him.  The guy Harry dueled at Bock Ordered Books was his future self.  Molly is Kumori, because (a) younger female sidekick Harry trusts, & (b) he needs the Winter Lady's immortality to use Mother Winter's Ways through time.

That theory has real problems with why FutureHarry would be curious to duel PresentHarry and see "what the Wardens are so worried about" & why he's disappointed to find Harry isn't stronger than he turns out to be, and why FutureMolly would ask what happened to his hand when PresentMolly already knows.  Weird things to mention solely for the purpose of misdirecting Harry if their identities are so very unlikely for him to have guessed anyway.

AFAIK, all Hunger Demons feed off negative emotions.
I think some sort of variant (that could feed off positive emotions) would be a very cool thing... but that's kind of the mortal schtick.  We are uplifted and empowered by our love, by our joy.

I think there was a WOJ that it might be possible for a whamp to feed on positive emotions, but they'd probably start to get 'sparkly'.

Their dietary preferences aren't ingrained, after all - Madrigal proved that by feeding on fear instead of lust. Presumably if they're willing to put enough effort and trial & error into it, other emotions beyond the big three negative ones are possible, with positive ones likely being much more difficult to change their attunement to.

It's probably not an accident that the big three are roughly opposite to the three virtues embodied in the Swords, though.
Lust vs Love.
Despair vs Faith.
Fear vs Hope.

I wonder if Skavis and Malvora tend to lose a lot more of their youth to never activating their powers than Raiths do ... I'd say a majority of people don't have their first sexual experience as true love (as much as they might be confused about that at the time), but blundering into scaring someone to death or tweaking them into despair enough to commit suicide would be rarer.

Morgan is supposed to be of Welsh descent about 200 years old, (the surname is a giveaway)so not really appropriate, he isn’t from Chicago, and it’s a failure to address that issue which is the problem. Besides setting up an recurring antagonist as black I found problematic, same if they tried it with Rudy.

Morgan's national background wasn't particularly fundamental to his character though, despite the name's Welsh roots. And in fairness to the original show, whether related to the casting or not, they did tone down his antagonism - he was still strict and suspicious, but without the seeming personal hatred of Harry. 

Granted I saw the series before finding the books, but "rational hardass" vs. "rabid" seems like a good adaptation change to me. A show would struggle with keeping a significant supporting character just an irrational persecutor for as long as it took the books to explain that behaviour.