/storage is the mount point for the Storage partition. All of the folders you listed are in the Storage partition, and can be accessed via the /storage mount point, ie. /storage/backup etc.
Texture Cache Maintenance Utility: Preload your texture cache for optimal UI performance. Remotely manage media libraries. Purge unused artwork to free up space. Find missing media. Configurable QA check to highlight metadata issues. Aid in diagnosis of library and cache related problems.