Sure you can find a bolt at Home Depot, Lowe's or even our Ace Hardware has a great bolt stock. It's a standard metric bolt. I'm not sure the size without crawling under there but you can easily match it up. Pick a grade 8 bolt as they're stronger.
The original fog light switch went beside the AC switch. The third hole was the rear defogger switch for the removeable hardtop. You can get the original switch from roo-sport.com or even look in our parts forum. There are two guys parting out their Capris that I know of. One of them might have it.
The fog light switch has two little wires that energizes a relay under the hood. The relay connects two bigger wires to power the fog lights. You'll learn big wire stuff it's not feasible to run the whole way inside a car to a super heavy duty switch. That's where relays come into play. Its like a small switch on the dash turning on a big switch under the hood. It also saves the manufacturers from running extra copper.
Your car is prewired for fog lights. You are just missing the switch, relay and lights.
Every aftermarket foglight kit I've dealt with come with a relay. Its law you have to wire it in so when you turn your high beams on the relay de-energizes turning the fog lights off. The foglights should come with directions how to wire it or you can probably find it on YouTube. But that's really not a big issue as you dim your headlights to oncoming traffic. You'd have to find the wrong prick cop to give you a ticket, lol. That and highbeams and fog lights on at the same time is a huge power demand on your alternator. Another good reason to have the fog lights shut off automatically.
Again your car is prewired properly so if you went with a stock switch and relay along with the stock wires hanging behind your bumper everything will work properly.
Relay 411... relays are pretty standard. You might find some with pins turned different ways so you buy theirs or it might have an extra pin to turn two things on. But for the most part they are all standard.
You'll see pin 30 which is your bigger wire going to the battery. Pin 85 goes to chassis ground. Pin 86 goes to your switch. That's the one that makes the relay click. Pin 87 goes to whatever you are turning on. In this case fog lights. Pin 87a is just an extra pin in case you want to turn two things on like 87 to left light and 87a to right light. Many relays have a diagram on them. You'll always see them pins 30, 85, 86, 87, 87a.