Можно ли использовать один и тот же кеш для squid

Наверное можно, но вообще я не слыхал про сквид для win32
Сейчас проверил, на стартовой странице squid-cache.org:
Squid is....
* ....
* designed to run on Unix systems
* ....

1.8 Does Squid run on Windows NT?

   Recent versions of Squid will compile and run on Windows/NT with the
   Cygwin / Mingw packages.

   Guido Serassio maintains the native NT port of Squid and is actively
   working on having the needed changes integrated into the standard Squid
   distribution. Partially based on earlier NT port by Romeo Anghelache.

   LogiSense has ported Squid to Windows NT and sells a supported version.
   You can also download the source from their FTP site. Thanks to LogiSense
   for making the code available as required by the GPL terms.

c00l!