Building builtin bookcase with TV - securing sections and routing power and cable

Hi all, I'm planning to build builtin bookshelves with a section for a wall mounted TV (on an extendable mount) in the area shown here: http://imgur.com/a/s01Cc

I'll need to route power to the middle of the wall to power the TV and cable box. This wall is shared as it is a townhouse. As you can see there are two outlets that would end up inside the book shelf area. Can I simply use an extender (http://www.homedepot.com/p/Electrical-Box-Extender-BE1-2/202708650) to bring the outlets into the lower sections? I was thinking I could then route an extension cord through a conduit that passes through the sections to get to the TV and then just use a surge protector strip to power multiple things. I'm wondering if I need to do it this way as:

1. I'm not sure I'm allowed by code to add an outlet to this shared wall.
2. If I can add an outlet, there's no easy way to tap off an existing one with multiple studs separating the middle of the wall from the nearby outlets.

What's my best bet for routing power?

My wife wanted the back to have a vertical plank look, similar to this so I was thinking of building the bookcase in 3 sections. What is the proper way to secure them to eachother as well as the walls/floor. I would cut out the carpet that would go beneath it.

Thanks!