Anime Questions regarding Mononoke

[Demondrake]

I only recently aquired the film a few days back since a friend lent me it (me = newbie). Personally, I think Lady Eboshi's voice, Okoto's voice (doesn't sound stupid anymore like in the Japanese version), and Moro's voice (doesn't sound like a male as it was in the Japanese version) were great improvements over the Japanese versions. Ashitaka's and Jigo's voices were ok. The rest of the voices sounded a bit too similar. I liked the beginning scenes much more than the ending scenes.

Anyways, I did come across a few questions that confused me. I was hoping someone could answer them for me.

*NOTE: THE FOLLOWING CONTAINS SPOILERS*

1) This is the one that bothers me the most. How does Moro lose her head before she bites off Lady Eboshi's arm? I doubt it's the black essense of the Nightwalker since that sucks life, not decapitate things...
2) How did San get her mask back? After she entered Iron Town, her mask was shot to pieces by two iron bullets. Afterwards, she still wore a mask, this one only with the top half...and it coudln't have been the original since there was only the ears and the wolf coat left on the original.
3) Why isn't Okoto completely surrounded by Demon tentacles like Nago, and why coudln't he talk like Nago could in Demon form? Is it because he wasn't in his Demon form long enough, and thus he did not complete his transformation?
4) Why didn't San keep her Demon transformation? Tentacles did sprout on her hand and forehead, but when Moro pulled her out, they disappeared. Is it because of the appearance of the Forest Spirit?
5) When the Forest Spirit healed Ashitaka's bullet wound, Ashitaka had no visible scars in his side. However, when the Forest Spirit healed his arm, there were scars, and there was a scar on his cheek. Why did only the scar from the bullet wound go away?
6) Does Ashitaka's Demon marks make him invincible? In one scene, where a piece of wood got stuck in his arm (on the roof when he tried to stop San from jumping down to fight Lady Eboshi), he just ripped it out. And in another, San stabbed him with the crystal dagger, but he didn't even seem to notice. However, other Demons are shown to be very mortal, as Ashitaka killed Nago single-handedly.
7) What's the significance of the similar jewelry that the Wise Woman and San wore? They both had large earings and a knecklace, though the Wise Woman's were blue...

I can't think of any more questions at the moment...I know I had at least one more...Oh well. Answer away. :)