2. In his definition of style I believe wood means that it establishes the way in which information is relayed from the screen to the audience. Style is the personality of the film, it can change how a it is understood by the audience.
I can certainly agree that Linklater's use of heavy collaboration in Before Sunrise works, I would be severely hesitant to believe it should be such a useful method for all, or even most, other films. It seems to me that it has its uses, but I can equally imagine it being damaging to a film. As far as the use of real life encounters in the film, the main example being the actors in the play about the cow, I feel it add minimal if any difference to the film itself. While the film itself certainly exhibits a sense of realism, I do not believe that is a result of such scenes. To me, that scene could easily have been just scripted, in other words it did not feel any more real than the rest of the movie, but perhaps that only attests to Linklater's knack at realism.
3. Film is a medium with a unique position of control on time. Movies can make time move slow or fast, they can skip over years, they can allow audiences to experience the same time in two different locations. The potential to manipulate time in movies is limited only by the ambitions of the person(s) making it.