Q. Is there a way to display only the incoming or outgoing volume of traffic for a specific interface?
A. The current implementation has no easy way to display only the incoming volume (or the outgoing volume) for a specific interface, however, you can trick it into giving that information on an interface by interface basis.
For instance, if you have subnet 192.168.10.0/24 on IFindex 5, you can select that exporter/interface combination from the dropdown, and enter the above CIDR block into the host filter. By selecting either 'receiving volume' or 'sending volume' from the selectors (next to the ports filter box) you will see the volume sent or received through that interface. The trick here is to filter by the CIDR block attached to the interface.