Is Twintania really a two tank fight?

[Cryvil]

I'm still not entirely convinced that two tanks is ideal, but this thread has certainly given me a lot to think about. Good damage on the conflags, better handling of the deathknights, a smoother phase 5 with a backup plan if the MT dies...all nice. But part of the reason I brought it up in the first place is because tanks are scarce and DPS are not. If you can't assemble a group in the first place, then it loses by default. Healers aren't so scarce...though my perspective is kind of skewed because I'm a scholar.

As far as solo-healing goes, and especially the question of how to keep your mana up, a lot of what a scholar does comes from free abilities. Then it becomes a question of whether everything else going on in the battle will kill the rest of the party. I have a few questions towards this end:

Do liquid hells come in even (predictable) intervals at phase 5?
Does a Paladin have the mana regeneration and time to prep stoneskin on himself once per death sentence?
Does DS vary between phases 2, 4, and 5?(Does the time between death sentences vary? Do they do more damage? Does Infirmity get stronger?)
What about her autoattacks and plummet? Do they vary between rounds? Does she stop attacking to spew liquid hells in phase 5?
(edit: Oh, reread the BG coloring book and seems the phase 4 one at least is delayed by Unwoven Will and Twister. So overall she puts out slower damage during phase 4? What about phase 5?)
If the MT jumps into a conflagration, what happens to the death sentence timing?
How strong is natural health regen?(if someone takes 1000 damage from liquid hell shots, how long will it take them to recover that if they don't use potions?)
DS, Plummet, and Divebomb are physical. Fireball, Aetheric Profusion, Hatch and Liquid Hell are magical. Correct?