But that offer was before she was injured...  I also doubt that even that job offer came without strings, especially if she because healed as a result.

Of course it comes with strings. Being a mercenary hired out to whoever Vadderung tells you you're working for, potentially including the likes of Marcone. That's still exponentially better than the Fallen's terms though.

And they're hardly likely to pull the offer over an injury that a valkyrie would heal from in, like, a couple hours.

Totally unrealistic if you know anything about Karen, she would reject the coin. She has enough knowledge, understanding and spiritual strength to do so.

Yeah, suckering someone into touching the coin is only really valuable with a wizard who'd sacrifice their powers if they just rejected it. A vanilla can drop it just like Sanya did, if their will is strong enough.

I'm not sure who exactly, but Lily, Harry himself and Rashid have listed Victor sells as one of the oddities happening lately.
I think that groinkick is correct. Upstart sorcerer who had access to more power and training than he should have, it's either Nemesis's work directly, or one of the circle. Which is more of the same.

Considering the WOJ about the first N-fected host appearing in GP, I'd lean heavily toward the second interpretation, that Sells, Denton and Kravos were pawns of a background player who's the true N-fected host. A skilled warlock or vampire with even moderate mental influence capabilities wouldn't find it particularly hard to warp a couple of self-taught small time practitioners and a vanilla into cat's paws.

Was it Lea who connected Sells, the FBI agents and riling up the ghosts(?) as sharing an origin?

If you meant that in the sense of was Lea the master who manipulated all three, I don't think it likely she was secretly infected way before receiving the athame.

Interesting thought, but from what I understand, the current consensus is Papa Raith gets his immunity to enemy magic from HWWB. Deirdre's Denarian was on Team Nic, and wouldn't cooperate with the Walker. Opposing agenda.
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From where we last saw her, Lara isn't in a great position. She could be persuaded to take more power.
Yes, the WN Deeps Battle devastated (not decimated) her opposition in the White Court, and let House Raith effectively take control. I imagine it will take the other houses decades or centuries to become contenders again. However, her House was wounded as well, and with Papa Raith (please make that a pizza joint) on a leash, the other houses were still somewhat beholden to her bidding. Their losses count as her losses in any conflict where the White Court would stand unified.
Also, remember Shagnasty. That Skinwalker waltzed right into Raith manor and made a field day out of ripping her personal guards apart in her very home. News of that demonstrates vulnerability, and news like that spreads. It also must have rattled her.

The Circle - who are all but confirmed to be Outsider affiliates - was trying to take Lord Raith out in White Night. It's possible that how the shield was set up means the Outsider(s) are stuck sponsoring it no matter who Raith is controlled by, so long as he lives. But I'm not sure the shield means he's necessarily still immune to everything Harry can throw at it anyway. Harry has learned a lot since BR, including getting better at recognizing Outsiders' handiwork, and that he has some sort of edge over them that other wizards don't.I'm thinking it might not be a coincidence that the death curse Margaret was able to tag him with despite his "invulnerability" was cast as she was giving birth to a starborn. Winter's power might be another advantage, given how hard it reacted to the other walker he fought in CD when combined with soulfire.

As for Lara' position, it's also relevant that Thomas mentioned in CD that the expansion in her power base has been getting scarily significant lately. I doubt she'd be hard pressed to keep Skavis and Malvora in line if she had to now; it's just that under white court culture she just prefers manipulation even after growing beyond absolutely needing it. Plus, there are probably other ambitious members of her own family that would decline to exactly fall into line.

I think sorcerer is more accurate...  As we saw in Storm Front, they can pull off a lot of magical stuff, but that doesn't make them wizards...

Cassius was probably at the upper ranges of sorceror talent, thanks largely to Saluriel's help and an extended lifetime to practice. But Victor Sells was a marked step up from Cassius, a full Council-level warlock who did spells in at least five different areas (the three-eye drug, calling and commanding the toad guy, the scorpion constructs, remote projection to speak and observe through shadows, and the heart-ripper curse itself). Harry figured at one point in the narration that they were probably pretty closely matched in strength, but his big advantage was that Sells' tutor hadn't trained him as thoroughly as Justin and Ebenezar taught Harry.

The way he put it was 'they were covering him at that point' which sounded more active, like a shield spell. But he seemed to be having trouble remembering what protection the question was about, so as you suggest, it might be better to take that not entirely word for word.

I guess interpreting it that his coven did the ritual leg-work to get a heavyweight to provide Lord Raith with his protection might still fit his answer, in the context of "No it wasn't Margaret who did that". It certainly makes more sense than one modestly talented but still less than Council-level sorceress and two barely more than vanilla helpers blocking strikes Ebenezar meant to kill someone with, and doing it so effectively that he attributed it to an old god.

His answer to if / when the Celtic gods (Tuatha) would appear was interesting. Somebody in book 19 and then otherwise not until the BAT lines up with previous comments that we wouldn't find out who or what Mac really is until very late in the series. A boost for the Mannannan Mac Lir theory?

Possibly in the 1800's the Council took a bit more of a relaxed attitude toward igniting a fire with magic and letting it spread mundanely to kill warlocks. WOJ was that still counts in the universal / spiritual corruption sense, but maybe it doesn't in the Council's legal sense. We know some of their laws that don't pertain to abusing mortals (specifically, against time travel and seeking knowledge of the Outsiders) are because those things are really bad ideas rather than because they're addictive and cause gibbering insanity. Maybe it works the other way for some things too.