I would like to use some networking/neutral shapes in 2D. Kind of like the Cisco ones that come in the system. If there are no more anywhere, can I import my own?
Yes, you can import the shapes you would like to. Here is the link that explains how:
If you are using draw.io for Confluence, it’s even easier. Click “File > New Library” and give it a name. Then you can drag&drop the file into the field. Or, you just drag it into the side bar: