Usually VIP fast pass can be used 2 hours after park opening and up to 2 hours before. In the summer I recall this is 11am to 9pm. You never hand them in, just show them to the CM. You also can bypass the queue of people waiting for this slot to go through the inital CM onto the ride. You get one each, not per group.
But still can only be used on rides with FP, is that right?