On the first point, I'm going out on a limb and assuming that the Good Guys will win. Has there ever been an epic fantasy where the Bad Guys have won?
On the second point, Rowling did indeed know how the series was going to end, but I don't know to what extent the stuff in between the beginning and the end was planned, and how much was discovered during the writing process. She may have found a number of diversions were necessary to get to her destination.
My argument is only that had the story of ASoIF been as meticulously plotted as Boaz was suggesting, GRRM wouldn't have given up after two years (or however long it was) on volume four and started again from scratch with a new plot structure. To stretch the analogy past breaking point, an architect doesn't change to a new style halfway through building his..err...building, but a gardener might drastically prune his...err...shrub (?) because he doesn't like the shape it's growing into.
I've just read that last paragraph over, and I think I have to go and lie down now.