"Answers" mark 3.

[Umbeliel]

Not quite. From what we can tell She is the spirit of aether in the land rather than the land itself. The world would exist without Her, but would probably not be able to habour conventional life.
I say probably, because it's clear there are things we don't know about Her yet.

No, I mean. The planet is Hydaelyn. As in that's it's name. "The Land is alive". Assuming she is basically the lifestream, it is a very safe assumption that "the Land" (Note that in the official lyrics it's capitalized- it's a proper noun. That is important.) and "Hydaelyn" as the floating space crystal are basically usable interchangably. Hydaelyn is alive- as the lifestream, she is basically the consciousness of the planet.