This is some good shit. re: 3), I think Hubert would generously bribe someone to freeing the beast in his place, but only after he's devised that remote way to kill it before the Nuckelavee becomes a nuisance again. Confirming or disproving the rumors about their supposed Cwyld immunity is potentially too important in his eyes.

Point 4 is hella good. A very powerful potion at the cost of mentally becoming a Nuckelavee for [duration.] He'll definitely be torn about using that one, even if the situation desperately calls for it.

Thank you so much for the answer! Hubert will be so disappointed that they aren't actually immune.