Maybe this would help a little, Winkey Page/Up or Winkey Page/Down switches the screen to the other monitor. And you could drag a program or window to the other monitor. A window can be dragged back and forth and metro apps or start screen can be moved to the other monitor using the Win/PUp or Win/PDown. I do not know of any way to dedicate the start screen to 1 monitor in an extended set up.
Thanks! I found that using DisplayFusion i can force a program unto a specific screen. If i have the location of "metro", basically what happenes when i press the win key this might work. Anyone know that location?