Note that while it is legal to have 287 lights if you like, only two forward facing white lights may be illuminated
when driving closer than 500' to other vehicles. I don't remember if the rules make a specific exemption for yellow lights such as some fogs... As an aside, true fogs used to be yellow until research showed that yellow had no advantage over white and actually was inferior to white in some circumstances.
In any event, when I am approached by someone at night who has particularly offensive driving or fog lights on along with their regular lights, they DO get a flash of MY high beams in response.
OK, moving on to something more important now...
It appears that mogur's 2-lights max in front is incorrect. I find a 4-light rule, with a dual-headlight pair (Low & High) counted as one light.
So, two highs, two lows, and two fog (or passing, or driving) white lights would be OK.
Apparently if the fog lights are yellow, they are (MAYBE) not counted in the 4-white-light limit?