3. Why might the director have chosen to include the shots of the landscape?

I saw this a long time ago. Still it holds up well to any vampire flick (Twilight ??) out today. Well that Scooby episode with the vampire was better than Twilight. Noserfatu is a silent movie hence Friedrich Murnau relied on landscape shots to create the mood and texture to his film. The film needed an ominous foreboding look to it. It also needed a sense of entrapment (can't get away) about it. The extreme contrast of black silhouettes in front of the light walls, threatening shadows, storm-beaten trees, chasing clouds and narrow paths, that lead to nowhere, were used by F. W. Murnau to give this film a unique look. Also, being in black and white, Murnau was able to use shadows and silhouette (trees, hills...) to great effect.

oops here is a source link I meant to add.