My '06 OEM foglights use a T-15 (torx) bit to access the bulb, a T-20 bit to tighten the fastener for one axis and another oddball bit with hole in it to fit around a post in the fastener for another axis and a 13 mm wrench for the nut that holds the light assembly to the bumper. Typically I have only had to use the T-15 bit and the 13mm wrench.
Yeah they used torx in a few different places that really make no sense. If you want to wrench on your rig you'll need a good set to include a torx 55. Other than that a good set of SAE and Metric 6pt sockets & wrenchs will cover 90% of what you'll want to do.