1.) No, at "in-home" ranges, accuracy isn't that much of a concern. OTOH, I would definately want to keep as many rounds or pellets on the target as possible to avoid giving the neighbors or the kids a wakeup call.
2.) Again, at extreme close range, it's probably not an issue. I've done quite a bit of shooting with a pistol-grip 12 gauge and have never had a problem,
3.) I just don't think pistol grips are really all that great (note, I'm talking about pistol-grips, not pistol-grip stocks, I like those). I guess what I'm saying is that if you like them and are proficient with a weapon outfitted in this manner, good for you .
4.) I just don't think they increase the utility of the weapon to any significant degree when you still have to have an 18" barrel.
5.) Now if I could have a pistol grip shotgun with a barrel that was only about 12" long (as seen in "The Hitman," or "The Punisher") that would be a different story.