Setup Firewall and Proxy server

I want to do the following:

1. Using IPTables for my firewall
2. Using Squid as Proxy and Web Caching (using default port)
3. Using Apache HTTP Server with Tomcat as Webser (using default ports)

All of thes components, are on the same machine. The combination of
Apache HTTP Server and Tomcat is up and running. Also, Squid is up and
running and some of the IPTables settings are activated. The problem is,
how to get them 'working all together'.

I tried to setup the following scenarios:
1. A second machine an my LAN (actually my Laptop) should use the Squid
proxy server to acces the internet, and acces the Web Server
2. All reques from the internet for my Web Server should be check by
IPTables, then 'redirect' to Squid for caching.

Who can help, to setup these scenarios.