How-to create physical connection for a Multiserver Setup for ISPConfig 3

[vaio1]

Hi guys,

I have read this article: A Multiserver Setup With Dedicated Web, Email, DNS And MySQL Database Servers On Debian 5.0 With ISPConfig 3 but I have not seen any physical network connection analysis. I have a technical questions:

1. Which is the best way to connect a basic network solution to the web?
2. How the physical network is connected between themselves?
3. Which are the main IPtables rules?

Attachment:
network: I have created a little pdf diagram.

Regards