Best HTPC setup

I've been dreaming up a set-up like the following:

In my theater/gameroom, I would have the HTPC, probably running some flavor of Linux with MythTV..

In my office area, I'd have the HDHomeRun connected to my cable line and directly connected to my router.. I'd also build a small UnRAID server for the office area to store recordings and act as a basic file server, and it would be directly connected to the router..

Here's where it gets a bit dicey and I'm not sure if it will work.. I'd like to extend my LAN to at least have a network drop in the theater/gameroom, so that I could directly connect the HTPC to the network and not have to deal with wirelessly streaming the data from the HDHomeRun and/or UnRAID server..

The main things I'm not sure on are:

a) Would I be able get live content from the HDHomeRun in this setup?
b) Would I still need some sort of tuner/capture card in the HTPC?
c) Will this work?