LolIf you just gave away the ending, I'm going to strangle you in your sleep.
Nah, I think he's just commenting on how Naughty Dog said this is more of a self contained story.
Don't worry about it.
Theoretically yes, that's the way it should work, although people have reported that the trophies aren't unlocking properly. For what its worth I unlocked the "Easy" trophy when I beat it on Normal.
Correct. If more are made which there will be, ND said they will tell the story of others.