What I find interesting is the River Song bit at the end. "But beware - it all changes now." I reckon we're going to see an adversarial relationship between them. I bet when they first meet, they're enemies, and will be for some time. But he'll remember her future then, and she won't (instead of the other way round) because we're moving earlier in her life and later in his.
Oh, absolutely. (Or, well, as "absolutely" as any guesses can be regarding Moffat's plans.) I'm interested to see how they can make her a believable villain, yet still keep her sympathetic enough that it'll be believable for the Doctor to later go through all the trouble to keep her mind alive at the end of the "Silence in the Library" two-parter.
And I still believe that the "great man" she kills won't be the Doctor; way too obvious.