Do they thread on pre ban barrels? Thanks.

I get mine put on but Kurtz in FL.  Since they all went on post ban 14.5" uppers they had to be permanent.  The customers liked them, I even have one on an M1A (pure custom).

I got one and had it milled to imitate the A2 birdcage.  KKF did it, he now offers his version so he won't mill the lavangs anymore.  Somebody will do it if he wont I'm certain.  

Regarding the function?  It functions fine, and is actually a nice FH too boot.  We shot several guns at night to see the diff in flash.  It worked quite nicely.  4" flame, dead space, golfball size fireball, not bad at all.  And this was not a bright flash either, a dark red IMHO.

What is KKF's web page? Does this actually reduce the noise slightly from the shooter? Thanks.

Yes it reduces the noise for everyone but the ones down range.  KKF has a forum on the Industry section of this board.  I did what I did specifically due to the noise and side blast of the Mini-y comp.