Orcs were originally Elves, yes. I have heard that they were tortured, and I've also heard that they were twisted, maimed, and other ugly things *shudders* before they became Orcs.
I believe that goblins and Orcs are the same thing, just expressed differently, as far as Tolkien and LotR go...
Uruk-Hai are a cross between Orcs and Men
which is terrible. "There is no curse in Entish, Elvish, or all the tongues of Men strong enough for this treachery!" They are larger and stronger than Orcs....
Uruk is Orcish for Orc; Uruk-Hai are the rebel Orcs from Isengaurd.
I doubt Orcs retain the Elvish immortality; i think they may live long if given the chance but i seriously doubt the actual forever-ness of it... Besides, most of them die in battle at the hands of Aragorn and the rest of all the good guys!!! WHOOP!
Orcs were made by Morgoth in mockery of Elves, and trolls in mockery of Ents. BUT ENTS ARE MUCH STRONGER! WHOOP!
Lol. I did not know i knew this much about Orcs alone.
I am kind of scaring myself
...
Hope this helped!