The supplied CANBus cable is 20 feet (6.1 meters). This is the maximum recommended length.
Yes, up to eight voice audio sources can be EQ'd, whether they're attached to the QOR or another Node.
Yes. There are two operating modes for the QOR's gateway: 12 inputs / 4 outputs, and 8 inputs / 8 outputs. Connecting an iQ6 to your console will consume two inputs and outputs.
Yes, you can EQ up to eight audio sources for mics, codecs, or other "voice-type" inputs.