1.) There are 3 wires that go to the O2 sensor, 12V switched power, ground and the 5V signal wire that you will need a pinout diagram for you harness to locate.
2.) No. Run the one O2 sensor to only one side of the motor. The 5V input signal it sends will be used for all cylinders. It needs to be closer to the cylinders than it would mounted be beyond the H pipe.
3.) You could call Solo PCM's in Florida and talk to them. If anyone can do the programming changes to add a second sensor, they could, but it is not necessary. You can run what you have once you add the O2 sensor.