A) Agreeing with Kestrel really. I think it's fine to have an individual need to do something, but that need should seem as if their idea or their only option. You should design the situation in such a way that of all the options, this one is clearly the one she would be attracted to -- you can do that by checking out the CS. If they do something a bit different, perhaps you can mold your plan a bit too. Anyway, forcing it on someone blatantly railroading them is not going to win fans. 

B) I think giving people the broad jist of the short-term is important to let them know there's something building. It helps to keep interest and inspiration up, otherwise some just think it's a lot of run-up. That said, revealing all too much will destroy the surprise behind your plot. Even if they need information open in the OOC, you don't need to tell them the repercussions of using said information. The next step might be clear, but the second is best in a fog.

C) You could pull that off fine. Not sure if you watch Doctor Who, but I think they execute prophecy beautifully in that the story is only bettered by it (without the surprise curbed). A companion will blatantly be told they will die, or 'The Doctor will die after the 4th Knock'. Okay shit, spoiler alert, right? Well, not really, because now everyone expects this and will be looking for it in the most obvious, and less obvious ways. You're able to throw in near misses playing to either prophecy. You're even able to twist the meaning of the prophecy so that, yes, technically it happens, but perhaps your definition of 'death' and the story's are tad different. The fact is you can use this sort of thing to your advantage with enough foresight.