Monitoring new file, or file moved or trashed in Finder

Dear all,

Is there a way to monitor if:

  1. a new file has been made/copied on my mac, and/or
  2. a file has been moved to a different folder, and/or
  3. has been moved to the Trash,
  4. has been deleted.

Basically intercepting the filesystem for any change.
This is “limited” to PDF files (but it would be interesting also for all kind of files).

This information I will then pass it to a applescript.

Is that possible?
Would this collapse my CPU usage?