Yes I agree that 5 planets would be to much. 3 it will be. As for score display "allied" , I'm pretty sure that even with a NA pact your score will be displayed.
I guess that clinches it for me, I won't configure the game for Score display "all". The only reason I considered "all" was because I hate the insecurity of not knowing what my neighbours are up to :-)
Yes you can try to buy info from other neighbours, but you'd have no way of knowing if the info you get is reliable...Oh well I use a Trader race anyway, so I'd be trying to establish treaties with everyone anyway.
Maybe I can become an information broker