On question 7. No and yes.
If range attacking, yes.
In close combat you have to brake away from combat to make it effective. You can still click but the monster will still see you so you are not hiding and can't get sneak attack. That is as I have experienced it with my shadow dancer.
They are a bit cheesy in NWN actually. A fighter/rogue/shadowdanver builed kicks ass from this place to another with no problem. And the worst thing is that you only need one level of shadowdancer really..
In PnP you need to be within 10 feet from a shadow source, your own doesn't count
