I'd have to agree...Wouldn't you want subs that have higher excursion, so more air is being pushed?
I am not sure. Probably for about 1/8th of a mile if not 1/4 of a mile.
I just stated that because you could hear it forever away. I am not sure what you would want for 10 ft. away.
That's really not that far, on a good day I've heard my system from over a 1/2 mile, but maybe it's because I have good hearing.