Regarding Question mark #1:
Here is the underdash wiring diagram for your 2000 Honda Civic LX.
It shows the ignition switch in the top left. The accessory wire you need is indeed 3 different colors depending on where you tap into it. If you tap in directly off the ignition switch before the underdash fuse box, the wire will be White/Black. Coming out of the fusebox through fuse #27 (to the radio) it is Yellow/Red, or through fuse #28 (to the cig lighter) it is Yellow/Green.
There also appears to be an "Option Connector" in the underdash fusebox that is also connected to the White/Black Accessory line. Perhaps there is a empty spot for a fuse there. It might be easy to just plug in there rather than tap into the wire.