Middle Earth "afterlife"

[Gothmog]

Elves cannot 'choose mortality.' They can be slain, and die from grief. That is all.

Actually they can. Take Luthien for example! She chose to become mortal and live her last years together with Beren. It was more complex than just choosing mortality, but that was the outcome of it. Because of her "labours and her sorrow" Iluvatar himself (through Manwe) gave her the choice to go back to ME as a mortal. It had never been granted before and haven't since, but it is possible to become mortal.

Elros and Arwen also chose mortality, but as there's Man-blood in their veins they might be a special case.

I think Captain Grishnahk offers us an interesting question concerning orcs, a question I've wondered about myself. If we go by the corrupted-elf theory, should they go to the halls of Mandos? I can't imagin filthy orcs in the halls were all the waiting elves dwells... But do they leave the confines of the world, like men? The unknown fate of the men was considered a gift, so why would the orcs be granted such a gift? I think I've heard a theory that stated that the orcs came to the Halls of Mandos, but to a part separated from the elven halls, but I don't know if it was based on any real information from Tolkien.

And what happens to the dogs? And cows and horses and cats and.... Do they just disappear? And what about Ents and Eagles, both inhabited by "spirits from afar", do they go to Valinor when they're physical body die? There's much to discuss in this topic...

If we assume that animals just disappear, that should been htat they are considered soul-less, or am I wrong? But what about a horse like Shadowfax, can he be considered nothing more than a transport from point A to point B? I think not.

Someone of the Masters in Lore of Tolkien on the site, please help me out here!