Squid Caches

Hi How can I find out if squid is using a file in the cache rather than just fetching the page everytime? Also, I was told you can setup squid, so that when the traffic of the net connection is low, that i can update its cache with new versions of the files if required. Is this correct?? if so how do i enable it? Gary _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.