Save your group to disk and it is thereafter available from the right-click menu and can be added to any network. This feature is useful if you want to reuse the same set of nodes and connections multiple times. See Save a ShaderFX Group Node to Disk.
Each time you update the ShaderFX editor, the scene view also updates automatically.
If you notice that this is affecting performance, you can change your settings to only update the scene when you choose to compute manually.
To do this, first enable Settings Manually Compute Graph, then choose Tools Compute Graph each time you want to manually update your scene.