Sorry for the rather short reply (the forum just killed a half a page worth of my post elsewhere and I'm out of energy): Tolkien himself was never completely sure about the nature and beginnings of the Orcs. He speculated a lot himself, and all that is there by others is pure speculation.
Landroval: Kibilturg, Taurunion, Erohtar... (Watchers of Elendil)
Crickhollow: Kibilturg (Tarciryan Knights), Zigilturg (Forever Notorious), Birnavor (The Northern Kingdom), Nuncle (Casual Wanderers)
Visiting elsewhere as Kibilturg, Urwendil... Born and raised on Imladris