When you say that the knobs are coming loose, are you referring to the knobs themselves having play and not feeling attached to the shaft or the whole pot moving when you turn the knob? If the knobs themselves are loose from the shaft, simply tighten the screw on the knob. If the whole pot feels loose and it's hard to turn the knobs, remove the knob and tighten the washer that holds the pot to the guitar and then attach the knob back to the guitar.
When you say "the bridge pickup somehow lost its threading for the necessary screws", what exactly do you mean? Is the pickup not able to lower or raise? If that's the case, then remove the screws that hold the pickup ring to the body (the should be one on every corner of the pickup ring), then replace the spring by unscrewing the 2 screws on the middle of each side of the pickup ring you just removed (order 2 pairs from Rich @ ibanez rules). Once this is done, put the ring back onto the guitar and voila.
If you however, mean that the screws that hold the pickup ring to the guitar are loose, then you need to go to home depot or lowes and buy a small container of elmer's wood filler. They come in a squirting plastic container and they'er about 2 bucks. Fill the little holes where the screws mount to the guitar and then let the guitar sit for a couple of days to make sure the filler has completely dryed. Once this is done, rethread the screws by themselves without the pickup ring, screwing them back with a screwdriver just enough so that you start a pilot hole. Put the screws back on the pickup ring and then screw them all the way in.
The pickup selector switch has a washer that attaches it to the body of the guitar. All you need to do is tighten the washer carefully (so you won't scratch the guitar) and the selector switch will stay in place. I would use either a long socket or a small adjustable wrench to do this.
Regarding the whammy bar... Go to your nearest Home Depot or Lowe's and buy a couple of rolls of teflon tape (they're about a buck each). Although you won't use a ton of tape, it's always good to have it. You'll need abou a 1/4" of tape to remediate the whammy problem. Start by pulling off the bar, remove the nylon bushings off the bar and then cut a piece of teflon tape (about 1/4" to 1/2", anything more and the arm won't fit). Take your time and wrap about 1-2 turns of tape in the opposite direction that the bushings go onto the arm and make sure it's nice and adhered to the surface of the area you're covering. Put the bushings back and then insert the arm back into the trem slowly.
I hope this helps.