2. There is no foreshadowing. At all. Up until the plot twist, there is absolutely nothing within the game to indicate any relationship between the protagonists. The whole thing comes out of right field and ends up seeming rather disjointed from everything that came before it. What’s worse is that in order to explain the obviously ridiculous nature of the situation, the writers introduce yet another deus ex machine plot twist (“The GFs made us forget”) which does its bit to try and salvage things (while leaving behind a head-ache’s worth of questions) then completely disappears from the game, never to be referenced by anyone ever again.
There is tons of foreshadowing, you just need to know where to look.

That's what I love about most FFs but aspecially VIII is that things are aimed at perceptive people.