Squid Newbie Questions

I appologize in advance if my questions seem trivial. I'd like to
give Squid a try to reduce the amount of bandwidth required for web
access (internet and intranet) but I have a few questions that the
FAQ just didn't answer for me.

1) How does squid work with cookies. Eg. my.yahoo.com where the
cookie specifies users and is required to update frequently (checking
stock quotes etc)

2) How does squid handle pages that require authentication? Does it
cache only the page code or auth info as well? Will the next hit
to that page also have to auth?

3) Is there html header info that specifies age info or is it only
a squid variable that determines how often to update a page?

4) What other caveats do I need to be aware of when implementing
squid for a medium size org (300 users).

I'd appreciate any help I can get on this matter. If there are
alternative FAQs, docs, or sources please point me in the right
direction.

Cheers,

---
Jeff Newton
Unix Systems Administrator
Computer Services
PMC-Sierra Inc.