Your English is more readable than many Linux documents!
As I said, I don't use squid, but it can be configured to use an "upstream proxy", just like a browser. That proxy could be one provided by your ISP or "localhost:8118" - privoxy. I don't know the details of how to do it, but it should be in the documentation.
Privoxy does not provide a cache, only privacy. It uses a number of configuration files, by default under /etc/privoxy: "config" defines how the service operates, "default.action" defines standard URL processing, "standard.action" determins how aggressive privoxy will be, "user.action" holds your own preferences and is the only file you should edit, "default.filter" holds search and replace strings for content filtering.
To stop privoxy scaning and/or replacing content, just define a class that disables all filters (-filter(...)), applicable to a wildcard ("*") URL. Define this in "user.actions" as the other files get overwritten during a software update. A "back door" is to set the "buffer-limit" option to zero. With no buffer, privoxy is prevented from doing any content filtering.
I use dyndsn.org so I can access my home site on the road. I don't know how this would work with TOR. I would assume that TOR provides some kind of "place holder" IP address and you would need to keep DynDNS updated if and when tht changes, just as with a DHCP connection. TOR would need to provide that information to you in some, secure way, possibly via SOCKS.
I'd reccommend getting privoxy configured properly first, then run it through TOR, then squid - stand-alone, then integrate the two. Then look at browser proxy (automatic) configuation and firewalling. External access could be handled in parallel.
There is only so much you can do to "disappear" from the Internet - packets must get back to the source and ICMP needs a route to work properly. The Internet was designed to operate under "external" threats rather than to avoid monitoring.
I reccommend you take a look at Ross Anderson's (Cambridge University, UK) security home page at http://www.cl.cam.ac.uk/users/rja14/
for background ideas. There is a lot of information, much of it is theory such as "how to run a completely illegal drugs auction on-line" (http://www.cl.cam.ac.uk/~rja14/cocaine.pdf)
. This "thought experiment" covers security and annonimity under the threat of prosecution i.e. real-world software.