I had the dealer install the in motion satellite system, it is called a Road trip mission and I believe it is compatible with dish or Direc TV however it will not receive digital from Direc TV, at least not last years model. Regarding the sound system, I took mine to a local shop here in Missouri and had them replace all the factory speakers, add an amp which was placed under the front passenger seat and a Kenwood sub under the small seat behind the stove top. The sound is a dramatic improvement. As another poster has suggested the sub is a ways back there but I'm able to turn it up enough to make it sound good in the front. There are plenty of adjustment capabilities with the in dash unit. I'm attaching a couple of pictures of the sub install which I did myself because the shop here just raised the seat and threw it in
You can get the 90degree bracket at Lowes and paint it black. You will have to use wood screws to attach to the sub but will need to use nuts and bolts to attach to the wood. I tried wood screws first and the sub shook them out. I don't listen to music very loud but those things really shake.