For 1; There should be links somewhere. Perhaps another method that may work is to compare popularity of soundtracks with their respective DVD/Blu-ray equivalent. It might be worth looking into. Evangelion ost on amazon and subsequent DVD/bluray sales It's EVA, it's super popular, so something went right?
For 2; Sorry man. Interpretation is hard in the art world. Analysis of classical music might give you some footing to stand on as it has been critiqued to no end with various input from people in the musical field. You may be able to draw something from one of their conclusions.
For 3; Bollywood comes to mind immediately. They live and die by their soundtracks. Lord of the Rings trilogy from Peter Jackson is a good comparison tool. I'm sure you can find something in that vein. Google search pulled up an 84 page dissertation into it. Here I have not read it but might after this.
For 4; Your teacher is right. However, so are you. This statement is more about "what could be used as a control?" rather than a "find a control." (especially this late in the game) The basis of all music used in film and television is that is has impact relative to what is happening on screen. Proving that is difficult but it is assumed in most cases. This is the best example I have ever come across that illustrates my point. It's the first look we have of Jurassic Park. It is THE REVEAL...and we are treated to poorly played melodica music that clearly does not match. If that doesn't suffice to prove a point, I'm not quite sure what else will.