On EndStone:
I'm going to clarify this, as this question went by where we haven't checked on what was answered on the FAQ thread so long ago. I'll repost there, too. End blocks aren't normally available in our world as there is no viable way to physically go there right now.
Faelin had written: "Not since some clarification of old, old lore. Ender materials with very few exceptions are not actually "matter" in the sense of a tangible material, and they cannot exist as such in Altera." I'll add in 'currently', at the end.
Endstone will be an exception, however, the "texture can be explained away as funny looking rock" - Faelin. It holds no special properties, does not glow, etc. I am aware some old players had taken some samples from past Exodus battles, it'd most likely be brittle rock. It should be extremely rare.