I had to instantly rewind and rewatch that scene four times because I was so overcome with the satisfaction of seeing the Putneys getting their comeuppance. Caliban calmly listening to them laying out their plans before delivering the beatdown made it even more magnificent.
"Yeah, I could murder the shit out of you…

I didn't expect the final battle to take all that long, for the same reason as you, but it did seem a bit… too easy? Yeah, I think that's probably how I'd describe my feelings.

"Even he couldn't believe how ridiculous and monstrous those people were."

OK, I must admit that the climax felt a bit anti-climactic to me, and I'm generally not too fond of the whole "let's break up the team at the end of the season and then re-assemble them in the next one" trope (though I'll reserve judgement until I see what next season brings).

Whether he's truly immortal (or let's say, has a theoretically infinite lifespan, violent incidents notwithstanding) I'm not absolutely sure about, but in episode 3 of season 1, he says this to Frankenstein:

That is of course a different question. Personally I'd really have liked to see more of Sembene's awesomeness, yes. Less screentime for Dorian and Caliban, more screentime for Sembene? Something like that, maybe.

They didn't actually give that much back story on Amunet (or maybe I just missed it).
The wiki article on her is also not that big: https://en.wikipedia.org/wi…

Ha, I couldn't quite put my finger on it, but yes, that was it!

Indeed. I once saw one of our instructors (army days) tear a vest apart with buckshot. Also a 2" door, and a pig's carcass. Was a fun day at the shooting range, but what I learned was:

It depends on the shotgun shell. We got to witness a demo by an instructor in the army a few years back where he basically tore a vest to pieces with a few shotgun blasts (two, three, don't remember if I'm being honest).
He showed us the pellets too, I was actually surprised at how big they were. I'd estimate it was…

That would actually depend on the vest and the shotgun ammo. We had an instructor do some demonstrationsin the army, and with high-power shells, the vest basically got eviscerated (don't remember specifically what the load was though, sorry; it's been almost 10 years).
He took more than one shot if I remember right,…

He might be playing the long game, see what she's up to. If he guesses that she's not very sympathetico with her mother, he might speculate that they'll go up against each other, thus making his job easier.

Well, if she's supposed to be several hundred years old, she still does look pretty young. Certainly much better than I'll look at that age.

If you go back and rewatch the season 1 part with his flashback… Frankenstein does not come off well in that at all with regards to his treatment of Caliban.

If I've understood correctly, Vanessa isn't outright possessed by the devil, she is the reincarnation of Amuneth, and if she mates with the devil she will birth the great darkness and bring about the apocalypse or something to that effect.

Plus, there's always the "supernatural beings can sniff each other out" magic thingy if all else fails.

Funnily enough I just rewatched season 1 today and the word gets a good mention by Sir Malcolm in the episode where they visit the plague ship.

Also, he was totally not remotely scared of her blood getting on him when they had sex in season 1. On the contrary, his interest in her only really got going once he found out she had tuberculosis.

And on that note, I loved the moment when Ethan handed the Derringer to Lyle.

Funny thing with Caliban: Considering he's immortal, he could just wait until the family drops dead. Not that that would be a very satisfying story, but still.