At my home, I have two desktop PCs in two rooms. The router / DSL modem is in one of these rooms. Now I want to configure a home server (having 2 LAN ports, running 24/7) in the corridor between the two rooms, using only one LAN cable at each door. This gives me the following physical configuration:

     (door)          (door)
 .----/-/----.  .-----/-/----------._ FritzBox
 |           |  |             .----´´ DSL Router
PC1         Server            |
                             PC2 

As just said, the server has 2 network interfaces and is running Ubuntu.

What I need now is a network configuration which enables both the server and PC1 to connect to the router. I think the server needs to serve as a bridge or switch.

Currently, all computers are configured having static IP addresses. If I'm understanding it correctly, a bridge / switch doesn't have its own IP address, but as the server needs to be configured as an own end device, it needs to have one. My first question is, do I have to configure both interfaces separately, giving both the same static IP address?

My next question is, how do I bridge the two physical networks into one? I have basic understanding (but am always confused again and again) of bridges and switches, but I don't know how to configure it in software. I only know that it's possible to do so :)

The third question is: Is it possible to configure this in a way that network packets from/to PC1 to/from the router only go through hardware or only consume low CPU in the server?

Can you help me? Thanks in advance!