Fate of dwarfs, ents, orcs?

[Tuor of Gondolin]

I tried a search on this topic, specifically on dwarves, but didn't turn up anything so, hopefully, it isn't repetitive.

Is anything known, either definitively or via JRRT drafts or speculation, about the fates of such as dwarfs, ents, and orcs. In a 1978 edition of the complete guide to Middle-earth Robert Foster says

The final fate of the Dwarves is uncertain. The Elves said that they had no life beyond Arda and the death of their bodies, but the Dwarves themselves claimed that Aule would bring them to the halls of Mandos, whence they will join the Children of Iluvatar at the End.

while in Letters #212 JRRT says: "...of the fate that
Iluvatar has set upon the Children of Aule beyond the Circles of the world Elves and men know nothing, and if Dwarves know they do not speak of it."

And he seems to also at least hint at the possibility of an orc "redemption", Letters #153:

They (Morgoth's using Valar subcreative powers to either make or corrupt beings in Middle-earth) would be Morgoth's greatest Sins, abuses of his highest privilege, and would be creatures begotten of Sin, and naturally bad. I nearly wrote 'irredeemably bad' but that would be going too far. Because by accepting or tolerating their making- necessary to their actual existence- even Orcs would become part of the World, which is God's and ultimately good.....and since in my myth at any rate I do not conceive of the making of souls or spirits, things of an equal order if not an equal power to the Valar, as a possible 'delegation', I have represented at least the Orcs as pre-existing real beings on whom the Dark Lord has exerted the fullness of his power in remodelling and corrupting them, not making them.

If, then, orcs were men or elves unwillingly corrupted wouldn't an eventual "redemption" of them be fitting?

Oh yeah, and what about the fate of the ents beyond Middle-earth? Were there rooms for them in the Halls of Mandos?