Cahce a webserver behind firewall

Our local system runs Squid to cache outcoming trafic, is it appropriate to
let this cache take care of incoming accesses to our webserver as well,
and secondly, will the access-control of Squid be enough or should we keep
the old firewall-software as well (for http-requests)?

And secondly, how about the IP-address of the webserver, will it then
look from the outside as if accesses were directly to the cache (the
web-adress points to the cache)?
 
Yours sincerely,
Erik Ehrling, f95-eeh@nada.kth.se

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at the Royal Institute of Technology, Stockholm, Sweden