Just about any 12v relay would work. I think places like Wal-mart and Meijer still sell Fog light wiring kits with a relay already in the kit, or just go to Radio Shack and get one there (that's what I do.) Auto part stores also often sell them. I just checked a few that I have laying around, and they're all 40 amp, which should be more than enough for fog lights. I think that must be a standard too, because I can't find any other amperages, and I used to wire tons of crap on my car using relays, so I have always kept relays laying around.
Wiring them is pretty easy. You will either have 4 or 5 pins on the bottom, each labeled with a number... 30, 85, 87, 86, and sometimes 87a.
30 = 12v output (to fog lights in your case)
87 = 12v input (from battery... This supples the majority of the power)
86 = Acc input (In your case, you bumper/corner lights)
85 = Ground (As stated)
For your wiring, you would not need 87a. In fact, I can't remember the purpose of the 87a, and I can't remember the last time I used it. Either 4 or 5 pin relay will work for you, just don't use the center pin on the 5 pin. I will take a picture tomorrow if I have time, but wiring a relay is pretty basic if you follow the 4 #'s listed above.
