Just my theory
Yeah. I'm figuring that Spectre will hibernate inside of Hal. It's done that before with other friends and hosts, not a full merging just going inside someone's soul and being inactive. This will allow Hal to be a Black Lantern AND use his life to resist the death ring and protect the Spectre.
The Spectre can resurrect people. Presumably, if we're right about the Rainbow Power of the White Lantern, the Spectre's god-power will fuel it and explain why it won't last since the Spectre will leave. Rezzing all the zombies is the simplest way to end an undead army. Then everyone will gang up on Nekron. :D
I'd surmise that anyone not in contact with the universe (possibly Crispus Allen if he's inside Hal?) or previously destroyed will not be rezzed. This will give SOMEBODY the opportunity to angst--probably the Bats since Batman will remain inexplicably dead.