Hello,
You can add your own cockpit or VC to a FSX plane by just adding the MDL file for the VC into the model folder of an existing FSX plane.
You should probably create a copy of the Model folder and make a custom selection to it so that you preserve the original interior model file.
For an FS9 plane, this is possible, but incredibly sophisticated, as it must be done 'surgically' (literally speaking) and perhaps only about 3 people in the world could do this, well, maybe 2 or 4. A model file is sealed, if you would, with crypted code work so as not to be breakable and taken apart. So adding a seperate VC is one of the most difficult things you could do. It has been done, but at what cost.
As for the TV view screen, I dont know how you could do this. I have wanted to figure out a way to show loops and movies and things for ages. But, if you have a special HTML FS viewer (basically a redone FS Kneeboard Checklist viewer) then I think you could load a MWV or the like into the seat model face, (basically like doing a VC gauge, mounting the gauge polygon on the seat).
You would need to create a gauge that was a HTML viewer that looked like a small LCD monitor, and ensure that it could play media through it, such as DIVX, WMV, etc.
Hope that helps.
Bill