1. How should I connect the copper electrodes to the arduino?
2. What general shape and/or size should the I cut the copper electrodes?
I don't know what size of shape to make the electrodes but I wanted to make sure you knew about this cool copper tape.
SparkFun sells two sizes.
Two Inch Copper Tape
5mm Copper Tape
The tape has a layer of protective material which needs to be removed in order to solder wires to the tape.
I used this tape to shield some wires but the shielding didn't really work until is soldered a ground wire to the shield.
I'm not sure how I removed the clear protective layer. I think I just scraped it off with an Xacto knife. I think steel wool or sandpaper would also work to remove the protective layer.
I only removed the protective layer from a small area. The area was just large enough to solder a wire to it.
This sort of copper tape might make it easier to make your electrodes.