How to Install Guitar Pickups

The pickup will often have two wires, (+) and (-). (+) is the signal, and goes to the middle lug of the pot. When you turn the pot all the way to the left, the middle lug will go to the left lug (and to the right lug if turned to the right). The left lug should be the ground, that way when you turn all the way to the left, the signal goes nowhere, so no sound. So get a wire from the left lug as well as the PU's (-) wire to the guitar's grounding point (often the back of a pot). The right lug is the output (all of the signal goes through if you turn the pot all the way to the right), so it leads to the jack. (Don't forget the jack also has to be grounded!)

You can use just two of the wires or more, usually 3, as you most likely have 4 insulated wires and one bare uncovered earth wire. Humbuckers have either 2 or 4 wires. The 4 wire kind are wired to allow you to connect each coil of the pair individually for coil tap/coil splitting mods. If you aren't interested in coil tap/split mods, then basically work out which wire is the hot for one coil and the ground for the other and connect these into your main harness as if it were a 2 wire HB. Then, cut and tape up the other two to stop them from touching any metal parts inside the pickup routing.

Springs determine tension of the bridge, assuming it's a Floyd Rose or something of that sort. Adding springs to this kind of system would make it tougher to use the whammy and increase the chances of you snapping the strings from playing or tuning the guitar. If it's a regular system, it does the same, of course excluding the whammy situation.