If I apply for an electrical permit, will an inspector call me out for previous unpermitted work?
This, of course, depends on the inspector. They will obviously inspect the work you're doing but they will be looking in your panel and can check anything that looks suspicious. I doubt they'd make you tear out anything unless it was a complete disaster and dangerous. They could make you repair previously done work if it was done incorrectly. As far as ripping all the old work out, that usually doesn't have to be done unless there's a total renovation in an area and you have really old wiring, knob and tube.