thumbnails, subtitles and internal HD recognition

1. How do I get Kodi to recognize the fanart for my movie files? I selected thumbnail as the display, yet only 1 movie displays a thumbnail of the movie poster. All movies in that folder have posters (fanart files).
2. I am using Kodi on the KDLINKS A300 media player. I successfully added a network location and Kodi scanned the files. However, I cannot figure out how to get Kodi to read the movie and music files on the internal hard drive in the media player
3. Where is the option to download subtitles for movies?