I think the questions about matching were answered.
In terms of grounding, either direction is fine, I would just make sure I mounted the i/c's the same direction (if they are matched). Most i/c's are grounded on the "to" side if I am not mistaken (and if I am, I'm sure I will be jumped on)--I would just want to make sure that my pre to amp interconnect shielding was grounded on the same side (amplifier) to prevent any small residual currents (ground loops, hums, etc.). If you hear no problems, then they are probably not present--don't sweat the small stuff.
