If you know where the shelf is that you want the cable box and DVD player, then a conduit is a good idea (hole to pull wires through). The electrical boxs and jacks add up in cost and are not necessary - it does make for a cleaner install however. The problem with the prewired is that technology changes and the variety of tv connectors is crazy. First we used coaxial cable, then composite video, moved onto S-video, upgraded to component and then the SVGA morphed into HDMI. That is about 10 years and 6 different cable types. I will say that there is only incremental improvement from component to HDMI but if you are doing 1080i from bluray - you probably want HDMI. Now - we are probably done with cable changes for a while but try pricing out a HDMI connector - I can tell you that I don't think Lowes carries it. Also - last I heard (1 year ago?) was that HBO and others will not let HDTV signal out of a cable box to HDMI secondary to piracy concerns. So you might have HDMI from bluray and component from your cable box. Don't care about all this fancy HDTV stuff - well someone in your household might in the next few years and a buyer someday might. Take home points - you can't(code rules) run the power cord for the TV in a "hole" - so put in an outlet. The slickest look is cable box and dvd player in a cabinet/closet so plan for a IR repeating system (to get the remote signal into a closed area).

I have both Apple TV / Airplay and Sonos. I use Apple TV for video, and Sonos for music. Sonos is a much better, comprehensive solution for music. You can still play your iTunes library through Sonos. You can also use streaming services like Rhapsody, Pandora, or Spotify. It is extremely easy to use - on par with Apple. The main disadvantage is that it is expensive. You can get setup for $350-400 at the low end -- $100 for a bridge that connects to your main home router, and then an entry device (Play 3) for your first room. They have options to let you buy an integrated speaker, or a pre-amp that connects to a home stereo system. As you buy more devices for more rooms, they have a way to group your speakers so you can pipe the same music to different speakers throughout the house, and it will stay synchronized. If you have a Sonos, it is much better if people have smartphones (iPhone or Android phone), because that's the easiest way to control what music to play. You can also control the music from a computer, or you can buy an expensive dedicated remote control.

Have you looked at IKEA? Here is a link that might be useful: IKEA TV Stands/Cabinets

The location of the switch is entirely your choice, limited by the structural members of the building and access to run cable to the switch location.