[Findegil]

In point a) and b) I agree with Aiwendil.
About c): I will try what we can do with this the text to bring in Aiwendil suggestion of Húrin killing Mîm with an arrow:

§273 (§3b) RD-EX-08 <TT Now therefore when those {Elves}[Men] approached the dwarf stood before the doors of the cave that was once the abode of {Galweg}[Orodreth], and he cried: ‘What will ye with me, O outlaws of the hills?’>
§3c (§274) RD-EX-09 <Sil77 But Húrin said: 'Who are you, that would hinder me from entering the house of Finrod Felagund?'
§275 (§4a) Sil77 Then the Dwarf answered: 'I am Mîm; and before the proud ones came from over the Sea, Dwarves delved the halls of Nulukkhizdīn. I have but returned to take what is mine; for I am the last of my people.>
<TT But {Úrin}[Húrin] answered: 'We come to take what is not thine.' Then said {that dwarf, and his name was }Mîm: 'O {Úrin}[Húrin], little did I think to see thee, a lord of Men, with such a rabble. Hearken now to the words of Mîm{ the fatherless}, and depart, touching not this gold no more than were it venomous fires. For has not {Glorund}[Glaurung] lain long years upon it, and the evil of the drakes of {Melko}[Morgoth] is on it, and no good can it bring to Man or Elf, but I, only I, can ward it, Mîm the dwarf, and by many a dark spell have I bound it to myself.'
§276 (§4d) TT Then {Úrin}[Húrin] wavered, but his men were wroth at that, so that he bid them seize it all, and Mîm stood by and watched, and he broke forth into terrible and evil curses.
§277 (§5) TT Thereat did {Úrin}[Húrin] smite him, saying:>RD-EX-11.5b Sil77 'Then you shall enjoy your inhertiance no longer,{' said Húrin; '}for I am Húrin son of Galdor, returned out of Angband , and my son was Túrin Turambar, whom you have not forgotten; and he it was that slew Glaurung the Dragon, who wasted these halls where now you sit; and not unkown is it to me by whom the Dragon-helm of Dor-lómin was betrayed.'>
§278 (§6)TT<But Mîm dying said unto {Úrin}[Húrin]: ‘Now Elves and Men shall rue this deed, and because of the death of Mîm the dwarf shall death follow this gold so long as it remain on Earth, and a like fate shall every part and portion share with the whole.’ And {Úrin}[Húrin] shuddered, but his folk laughed.> TT<‘We came but to take what was not thine - now for thy evil words we will take what is thine as well, even thy life{.},'>RD-EX-11.51b<editorial bridge said Húrin. And it is sung that
><Lay of the Children of Húrin {The}the dawn over {Doriath}[Narog] __ dimly kindled {695}
saw {Blodrin Bor's son}[Mîm the petty-dwarf] __ by a beech standing
with throat thriléd __ by a thrusting arrow,
whose shaven shaft, __ shod with {poison}[iron],
and feather-wingéd, __ was fast in the tree. [5]
He bargained the blood __ of {his brothers}Túrin's band for gold: {700}
this his meed meted - __ in the mirk at {random}[Narog];
by an {orc-}arrow __ his {oath}[curse] came home.>
§279 (§8) RD-SL-05 {And the curse came upon the possessors in this wise. Each one of Húrin's company died or was slain in quarrels upon the road; but Húrin went unto Thingol and sought his aid, and the folk of Thingol bore the treasure to the Thousand Caves.}<TT Now {Úrin}[Húrin] caused his followers to bear this gold to the halls of {Tinwelint}[Thingol], ...

I had to take some speech from the Sil77, but I think it reads not that bad.

Respectfully
Findegil