So I dug around some more for some more answers. (I would add links but, the answers I found are over on the Henchmen Forums.)
Question One: The length of time the Flame Pillar created by Immolate lasts.
The answer is that since it is not a piece of terrain that was created, (ala Ice Pillars) It stays around until the closing phase.
Question Two: Does a model that has the Flame Pillar place in based to based/on it's head take the damage flip.
At the moment yes, they count as having entered the Flame Pillar had thus take the damage flip.
I hope that clears things up a bit more, I will keep to my ear to the ground for anymore info on the topic.