u should configure device definition for the devices u want to block. just select "USB" from device deffinitions parameters...
hopefully it will work. for more help read this
USB printer, mouse, keyboard etc. do not come under removable storage definition. Those are plug and play device. So as long as you are not creating plug and play device rule for USB, it won't block printer, keyboard, mouse.
And for CD/DVD we have an option under removable storage definition which can be used.