I think it would be good to ask yourself the question: "does this film tell a story?" Whose story does it tell? Who tells that story? As long as you can answer these questions, you can use narrative analysis. What is more, film study can not only be based on sequence and dialogue studies but also on SCRIPT studies. So, my answer would be, definitely yes :)
No I don't think so, because narrative analysis is done for the narrations in natural setting. the dialogues in films are scripted. Discourse is better option.
Fiction is structured around a narrative, and how that narrative is related is a valid question (narrative, by the way, is not limited to what characters say and do).
But there is also a plastic aspect to film (image composition, use of movement, editing, lighting, sound...) which can be an end in itself, either as a way to carry a narrative or despite that narrative. What a film shows is not reduced to what it says.
What makes narrative (and discourse in general) so zeffective in analysing film is it time related structure. There is a beginning a middla nd an end to a film as there is in a book. How they are presented is a practical 'hook' for grasping the meaning of a film.