"Ricardus" is his Latin name. Since the Others speak (or did speak...) in Latin, I'm assuming the Ajiira folk are old others of some kind. In any case, they have an obvious connection to Jacob. I don't think AliveLocke is the smoke monster. I'm pretty sure that's a third entity altogether. When Ben told Locke he had to do whatever Locke said b/c the smoke monster told him to in Alex's form, Locke seemed genuinely surprised and pleased. When it was asked why the Ajira folk were lugging DeadLocke's body, they said it was to show what Richard and the Others were up against. Since they know about the smoke monster and can apparently summon it, I think AliveLocke is something more evil....or maybe more good? We still don't know who's good and who's bad. Is Jacob the good guy and DudeFromTheEpisode'sBeginning/AliveLocke (they're obviously the same person) bad or vice versa. We still don't even know that answer for Ben and Widmore to be honest.
I do think the religious possibilities (Jacob and Esau) are interesting and compelling. In the Old Testament, Esau and Jacob are twins. Esau sells his birthright to Jacob for some red stew or something b/c he's really hungry. This pisses off God who basically exiles Esau for so lightly giving away that which is most important. Maybe something similar happened here. The guy in the black robe from the beginning ran the island and for some reason passed on that power to Jacob or Jacob took over. The guy realized his mistake and wanted to kill Jacob to reclaim the island but b/c of some strange set of rules could not.
Now, the rules are obviously significant. Remember, Widmore supposedly broke the rules when Keamy killed Ben's daughter. It seems that Ben and Widmore can't kill each other, again b/c of some kind of set of rules. It would be WAY too coincidental if these rules weren't linked to the rules that prevented Black Robe guy from killing Jacob.
Also, the conversation between the Black Robe guy and Jacob is still confusing me. I can't make any sense of it....