Oh wow, so many questions, so little time.

As to how a prophecy is made, no one really knows though some say that the Seer falls into a trance-like state enabling them to see "clearly", which means they can see everything in front of them, around them etc. By this they can "see" things which happen before they happen though they have no recollection of it happening.

What powers be in play? Well, again it depends on yuor religion I guess, whar you believe in. I don't want to get into that here since I know it's a soft topic for some. But I guess it would also depend on what kind of state you're in, your mental state I mean, could you handle what you see, or would you become crazy-ish?

How a prophecy comes out, well again this is a toughie, I mean you can't say "hey you,you're supposed to do this..." and have it happen right? No I think it's fate, the step of events which lead to the prophecy, what road to take that kind of thing.

That's all I can think of for now, I'll come back later with more

(wow I just sounded smart )