I say install the wires becauses one controls the backup camera if you ever want to install one. The other speed control wire, from everything I have read ie all the internal caculation of the units speed/distant/time actions more accurate. Also, a lots of problems that people have are related to not hooking up this wire. If you have to call in for service on the unit they will talk you throuh the menu and the unit will tell them the wire is not connected. They will not be able to help you with a problem without the wire hooked up.
You can live without the wires hooked up. Your choice. I just think it's best to hook it up right the first time and work from there. My Sirus in on the right side kick panel. Just pull the glove box and you can get to everything easy. I looked at Blue.. but I don't talk enough in the vehicle to make the install. I have a I pod hookup and it's great. After you get everything working put in your own custom background and enjoy.