A traditional student is one who follows the commonly accepted student trajectory. They graduate high school, the following fall they begin their undergrad, four years later they earn a bachelor's then begin grad school. Living and expenses for a traditional student can be with parents or on campus. They are typically not married and have no children. Race, color, ethnicity, religion, sexual orientation, and gender orientation do not generally count when determining traditional or nontraditional status. However, for the purpose of affirmative action many schools document those demographics--and including some sort of boot-strapping experience from your life that pertains to those demographics in your statement can bode well in your favor. However, being def, especially if you are hearing in one ear, is a touchy subject when it is lumped in the category of disabilities. (for clarification to what I mean, read ch 2 of Andrew Solomon's book, Far from the Tree).
Income, as far as I understand, only applies to nontraditional students who are 100% responsible for their tuition. For example, you do not include your parents financial information on the FAFSA, you have to qualify for grants on your own, and any loans you take are solely in your name and not co-signed for by anyone, and no one else is making tuition payments on your behalf.
I am a white male too, but because I started school after a career in the military and in food service, and then got married and had children, I am a nontraditional student. If I were a nontraditional student who was not white, not male, and if I had a disability that was not a learning-disability, writing about that would likely escalate my application--assuming GPA, LSAT, Resume, and LOR's were strong enough to get into a decent enough school.
Typically, law schools want you to explain why you are awesome, without you actually saying you are awesome. You should tell a story that illustrates why you wish to pursue a career in law, as well as what attributes you will bring to the classroom, all within a personal experience. Top Law Schools has a list of different methods and styles of writing statements with samples that include detailed reviews of the samples. http://www.top-law-schools.com/statement.html