There's a lot to your question. Guess that's why some businesses are formed largely to or exclusively for reed system development.
1. As fatty said.
2. There are different styles of reed cages and reeds. The rad valve from boyesen is a two petal reed sitting on a 45º cage. The delta forceII consists of an
eight petal reed sitting on a 30º cage...actually
two cages stacked atop one another. The dfII also has adjustable reed tension blocks (hi-lo) so you can set the tension to suit
you. That simple adjustment makes a
huge difference in the way the bike works.
Look around on the web (like
http://mototassinari.com/) and you can see pictures of the two for comparison.
Obviously the above described reed valves will not act the same. There is much more reed tip area on the delta force than the boyesen and the º of the cage effects the rpm range at which each will work the best.
There are also choices of reed composition, mostly fiberglass and carbon. Within these classifications there are different designs having to do with reed stiffness, edge coating, single/dual (one may sit on top of another) and the like.
Oh...and besides the reed type/composition and the angle of the cage, there is the intake portion to deal with. Boyesen says the rad valve was specifically designed to resolve carburetor mounting-angle problems. Note that on most bikes the carb is pretty wonky compared to the cylinder.
You can deduce that, sitting smack dab in the middle of the air/fuel stream, a reed system can have a tremendous effect on how your bike works.
And so it does.