2 way or 3 way
#2
I think you'd find that the sound would be a bit too "bright" with a surplus of tweeters, but that's just my humble opinion. I'm sure the folks with the gazillion watt systems will chime in with advice on this.
#8
correct but your staging needs to be at ear level which is why people started putting tweeters in the pillars. with good staging you can overcome the tweeter driver separation