Apparently it's still up in the air if this coming back or not. My lovely lady has heard that the Sci-Fi... sorry Syfy
Channel has made them a tentative offer for a four part miniseries to wrap things up.
My take on your questions, Matt...
First, they kept saying for ages that it was this big deal to fuel "the array" that transported things. It felt to me like it wasn't so much what the array was capable of, but what it was capable of at its current power levels. Every time they'd teleport a bus or something, it'd knock all the levels back down to zero again and they had to start over. So the issue was more are we going to be able to get this thing to power level X in time to save our world.
Again, just how I understood it. Very well could have the whole thing backwards.
I think points two and three are kind of linked. There are going to be massive earthquakes, floods, etc. Sophia pretty much said so. She was trying to wipe out humanity a a mercy killing, rather than make the whole planet suffer through what comes next.
I would guess that the homeworld is probably dead. The same radiation that was endangering the people would've wiped out animals, plants, bacteria--the whole biosphere. But now that it's out of harm's way it's probably an okay place to wait until things settle down a bit on Earth. Then we transfer everyone down there, the homeworld breaks up (or gets sent away), and voila
...Inherit the Stars
-- the updated, aggressive version.