People are saying Ning was hacked, but is that for sure? Did Satoshi's computer get hacked, did the Ning get hacked, what happened? We may never know, but for me there has always been a non-zero chance that Satoshi's coins could move. I don't know what the result of that would be.
2) A new hope to find out his identity. He couldn't really pay someone anonymously without using a tumbler, the tumbler he'd use would gain a ton of PR and could become the quasi-official Bitcoin tumbler.
3) Depends on the amount, but I think there'll be a great fear that he could move all of it - that amount would almost certainly being the Bitcoin economy down since its value is (I think) based on the assumption that the coins will never move, so the BTC price would decrease sharply.
That's my guess.