from what i can tell, the full-rides are given to the people with the strongest numbers, and soft factors come into play if the scholarship is for a specific goal (like public interest, or bringing people of a certain character to the school who might not otherwise go). i also hear that scholarships (especially for jd candidates as compared to med school or other grad schools) are even more competitive than getting in. (great. that's just great.)
not all schools calculate your parents info, but it depends on a lot of circumstances, like your age, how long you have been independent, and the school. some of the schools on my list insist on getting parental info regardless of marital status or age (which offends me personally). still, i dance their dance because i will take whatever money they give me if i attend.
your best bet is to check each schools website for scholarship and fin aid info.