It depends. Directors are the ones who tell everyone else what to do. Cinematographers are responsible for lighting and such, but they're working off of what the director has told them to do. Same with the scripts. Directors can make on the set changes to dialogue and such or even have rewrites before shooting begins. It holds for editing, music, actors performances, costumes, etc. A lot of it boils down to how much power the studio and producers give the director. Spielberg and Kubrick are perfect examples of directors who control every aspect of their movies and shape them to their own visions.
Yeah, pretty much. In addition, a lot depends on just how good (or bad) a director is. A middling director is going to be as good or bad as the people around him or her. A guy like Scorcese, Eastwood or Nolan is going to put his stamp on something and elevate it above the genre. Conversely, no matter how good your actors and writers are, if you get someone like Uwe Boll to direct a film it's most likely going to be shit.
