New X-Men/Headscratchers

How did Cassandra Nova come back from the dead, and why isn't she evil?
What happened to her between her defeat in "Imperial" and her apparent return in the future of "Here Comes Tomorrow"? And what's the connection between her and Ernst? Is it just a coincidence that Ernst is named after Cassandra's favorite artist? Even if Cassandra was somehow reformed, how is she still alive that far into the future?

Why did Sublime choose Beast as its host?
In "Here Comes Tomorrow", we learn that Beast was possessed by Sublime because he became addicted to Kick, and that Sublime used him to conquer Earth. But previously, Quentin Quire and Magneto both became addicted to the drug as well, but it only made them act violent and erratic, and ultimately made them bring about their own deaths. Both of them are Omega-Level mutants with vast destructive powers, and Magneto is a well-known mutant leader with a huge army of followers. Though no pushover, Beast's only mutant powers are enhanced strength, agility, and senses. If Sublime was really hell-bent on taking over the world, why would he use Beast as his host instead of Magneto or Quentin Quire? And for that matter, how did Beast manage to take over the world without any of Earth's superheroes stopping him?

How did Wolverine get trapped on Asteroid M?
We never see how he ended up on the asteroid after Weapon Plus' space station blew up, so it gives the impression that he just drifted through space and landed there by coincidence, then tells us that it was a death-trap set by Magneto. Even if this was planned by Magneto, how did he plan it if he had no way of knowing that Wolverine would be on the space station? Remember, Cyclops and Wolverine went there after Fantomex went out on his own and drafted them into an independent mission--none of the other X-Men knew about it.

How did Magneto's infiltration plan work?
Morrison has claimed that there's plenty of foreshadowing about Xorn's identity in early issues. I've never been able to find any, but there seem to be a few details that actually contradict it. Specifically:
 * If Magneto wasn't really in Genosha during the Sentinels' assault on the island, who was that tall, white-haired man in the capital building?
 * Why did the guards at Feng Tu prison try to sell Xorn to the Sublime Corporation if they knew his true identy and were working with him to bring down the X-Men?
 * How did the guards pull off that demonstration of his powers that they gave to Sublime? At the very least, shouldn't Sublime have been surprised to see that "Xorn" was a white-haired Polish man when the guards pulled his mask off?
 * When Emma scanned Xorn's mind and saw memories of his childhood in China, whose memories was she really seeing? How did Magneto create a set of fake memories?
 * How/why did he have that conversation with the old man in Chinatown about his childhood in China?
 * How did he heal the X-Men when the nano-sentinels were infecting them if he didn't really have healing powers?

How was Magneto able to kill Jean?
Granted, Magneto's a powerful mutant, but how is he powerful enough to kill someone who's bonded to the Phoenix Force? How is it that she could survive being thrown into the sun, but was easily killed by Magneto (who, at that point, had just taken a full-power force beam to the face from an enraged Cyclops)? How is it that Rachel Grey could beat Galactus in a fight when she was imbued with the Phoenix Force, but Jean couldn't defeat a guy with magnetic powers?