Logitech MX-1100 Mouse Questions

So I'm looking at buying a new mouse, and the Logitech MX-1100 has me very interested. A couple questions though;

1) Are the DPI buttons customizable in OS X through the Logitech Control Centre application? Does SteerMouse or even USB Overdrive recognize these buttons for customization (I don't care too much about dpi settings).

2) I've noticed in some stores the mice on display often time have the scroll wheel spin completely without any clicks, you can literally spin the scroll wheel and let it glide for a moment. But there are others that click with each push and don't spin. Are the ones that spin freely defective or something? What gives? I prefer the free spin, since its completely silent (like the Microsoft mice) but something is throwing me off here.