1) The Windows Task Scheduler service along with the DLO Change Journal service.
2) DeDupe occurs only when the file is completely new, meaning the first revision of the file will be deduplicated. Once this file changes, the backup mode switches from DeDupe to Delta. And Delta mode requires the DUDF (Desktop User Data Folder) as the delta changes are first computed on the DUDF and then copied over to the NUDF (Network User Data Folder).
3) Delta File Transfer is a compression technique which transfers only changed portions of a file from the DUDF to the NUDF.
4) Use VSS method for backing up .pst files. - http://www.symantec.com/business/support/index?page=content&id=TECH202413
@CraigV - the kb which you posted isn't applicable (it applies to BE-DLO) and VSS method wasn't existent then.
5) General option is like a global setting which is applied to all profiles. However, what ever you select in each profile individually takes effect.