Yes you can use the 24-70 L on a Rebel. Nice lens.
The lens has USM (ultrasonic motor) focusing, not USB.
Compact Flash is the type of storage card your camera uses - has nothing to do with the lens it will accept.
Your Rebel will work with any Canon EF or EF-S lens.
The EF 24-70L will work on any Canon EOS camera. The new mirrorless Canon EOS M requires an adaptor to use EF or ER-S lenses.