Is it possible to add a USB Scanner/Printer or through the network?

WD Legacy Products Sentinel Products
1

I need to get scanned documents to show up on the drive.

2

Depends on your scanner I guess.  If you can tell the software where to save the file, you should be able pick a share on the server.

3

On my HP Color LaserJet 400 I have an option to send the scan to a folder, which I have set to my DX4000. It works well.