Okay, Blackest Night #3 gave some new insight to the Black Lanterns themselves...
[HIDE]Apparently, according to Atom, they aren't necessarily the dead brought back to life. He theorized that the Black rings replicate certain things about their chosen targets, including their memories and whatever powers/abilities they had in life. So it's more along the lines of the rings wearing the dead instead of the dead wearing the rings.
Indigo-1 of the Indigo Tribe revealed that The White Light came into being sometime after the creation of the multiverse and existed for 700 years after. Then the darkness that existed before fought back against it and splintered it into the seven emotional spectrums that exist now. Also, every living being in the multiverse born from the White Light contributes to the seven spectrums, which can collected and condensed into power, as shown by the Seven Corps out there now. Indigo-1 also revealed that the Green light of Will when reinforced by another light, like that of the Indigo Tribe can neutralize the Black rings and leave them vulnerable to conventional damage. Once a Black ring is destroyed, the feedback created from that renders the Black Lantern inert. The more shades of the emotional spectrum that shine together, the stronger the light produced.
All seven spectrums working as one can reproduce the White Light and destroy the Black Battery itself.[/HIDE]