How exactly does Respawn in Base Data work?

Is it a respawn of the NPC? If so;

How long does it take to activate?

What conditions? ( on load? )

What if the NPC has been "markfordelete" ?

OR - is respawn only in reference to the items in the NPC inventory?

As I understand these respawn every 3 game days.

It seems to be the case that a persistent reference with Respawn checked ( like the template NCR trooper ) could be dead, constantly in the gameworld, and respawning loot every 3 days...

Is this actually the case?