Is installing the standard fog lights on a celica that wasn't manufactured with them difficult?

Would it be as simple as removing the peice of plastic from where the fog lights are meant to be, inserting the new fog lights and wiring them up?

Also, how do the fog lights turn on/off? Is it automatic, or will I need a switch of some sort?

on celicas that have fog lights there are special metal brackets that hold the fog light. These are bolted onto the main front cross beam. You could probably make your own up though.