Let me add my welcome to the chorus already here... And Front Ranger beat me to it, but I'll say it again... Want a cup of coffee don't you? And a piece of cherry cake?
I agree quite a bit with what's been said here so far - that Lureen keeps lightening her hair, literally, to try to feel attractive/get Jack's attention and figuratively, to me, because she symbolizes fire and her hair getting lighter and lighter is symbolic of her fire going out and turning to ash.
This is my favorite interpretation of Lureen's hair situation. I love, love, love, the idea that she goes from red and white to black and white by the end. Gradually her reds get watered down and the impact really is something like fire dwindling to ash. I'm not so sure her desire to dye her hair as to do with getting Jack's attention. I think she wants attention, yes, but in a general sense. I think she's resigned to the distant relationship with Jack quite early on.
Kallyn, there are all sorts of fun discussions all over the place about the different colors that seem to be associated with different characters (those are big topics and I'm sure you'll have fun discovering all those nuances). Lureen's hair is a really good detail to notice.
And, congrats, I hadn't heard the headlight discussion come up before either. You're certainly correct that almost any detail you can think of in this movie/ story is loaded with potential significance.