No, the unit can not be cascaded. However the KD-MSW4x2 can.
The KD-MSW4x2 has RCA connectors where as the KD-MSW4x2PRO has BNC connectors. It also has analog left and right volume control and can be cascaded for more than two outputs.
When using good quality coaxial cable, component video signals should be able to reach distances of 300 feet.
No, the volume control is only for the left and right analog audio outputs.
Yes, the unit does support both digital and analog audio at the time but only the analog audio channels have volume control.