Traffic Shaping

I am a little unclear on the queue.  If I have 100 users and 10 are priority.  I set them all up on a 4 meg pipe.  then set up two queues that feed the 4 meg pipe.  one queue has a weight of 70 and another with a weight of 30.  The 10 priority users point to the 70 and the 90 low proirity users point to the 30.

Question 1   What happens if all 90 low priority users are online and the 10 priority are not.  Is the full 4 meg pipe utilized or is on 30 percent utilized? 

Question 2.  What happens when the first priority user jumps on?

Thanks,
 Mark