Legal Issues with providing Free WIFI access to public

I work for a small municipality who wants to offer public wifi access.

Would appreciate any direction on the possible liabilities incurred by an
organization that provides free public WIFI access.  I'm really looking for
some legaleeze as I have looked at the "what if's" and "hypotheticals".  

Would a simple banner page that identifies the terms/conditions and that a
user acknowledges for access hold up in court (US).  Examples?

Would my organization be classified as an ISP (and subject to their laws)
even though the service is free?

Is my organization liable for any public activity or crime committed by an
individual using this access.  Including law suits?

Does my organization have any responsibility to notify users that the
transmission of information may be unsecured and monitored (virus).

Can I block access to sites that my organization views as malicious, illegal
or inappropriate?

I do realize that any sites/activity engaged by users of this free service
would represent my organization and open me up to possible slander and
blackmail.


Thanks for any help>-jeff