I'm a newbie... what is fun_plug and where can I find it? Is it better that the DiskClone Pro backup s/w that comes with the NAS?
fun_plug is a text file that sits on the root of Volume_1 of your NAS. When the NAS boots, it executes any commands within that file. Because of this, it has allowed third party scripts and tools to run on the NAS. The most popular of which is Fonz Fun Plug (FFP). Modifications like this are totally unsupported by DLink. That said, with proper backups of your files and a bit of caution and know-how it's quite safe.
Google Fonz Fun Plug for more info.
Out of the box, you can use backup tools to backup to the NAS without these modifications. I use Robocopy, which comes with Windows Vista and above and available to install on XP. SyncToy is another free Microsoft offering.
If a drive fails, you will get an email if it is configured to do so. The drive light will also change colour.
A recycle bin facility does not exist. Nor does a versioning system.