1: There have been some threads about this. To my recollection you remove the batteries. Then pry out the switch, short it out, and put it back in. Then you connect wires to the battery terminals and close the bottom back up. It probably requires a hole for the wires, I don't recall. Then connect your light cycle to a 5v source and it will be lit up.
2: I defer to the crowd here.
3: The PIG 2 has 4 standard IN's, 1 GI input, and 2 Aux IN's for things like reed switches and external buttons. It has 4 OUTS and 2 Servo connectors. With non-creative wiring, you can connect 4 mods to 4 signals (switches, lamps, GI, motors, flashers, etc) and control 4 mods (12v and/or 5v). You can control a whole bunch of stuff with a single PIG 2.
4: This isn't a question you asked, but you're only an hour from me so if you get in a pinch I can always drive down and help you out.