-You can solder them right on. It is not the best thing to do, but it works. I would use a wireharness. It makes things easier later on.
-You can hook up a wire directly to the battery, of course you have to fuse it.
-Power wire is the wire that is constantly receiving power. It powers the unit for saving the time, the radio stations...This wire is yellow.
-Ignition power wire is the power that turns on when the ignition is on. This wire is generally red.