The NASA Robotics Alliance Team has done a wonderful job at explaining the different grants available, eligibility, the rational, and the steps needed. I would recommend that every team read this document over.
Information about Demographics for a school ( % receiving free lunch) can be found at:
http://nces.ed.gov/globallocator/
Hang on to this information as it will also be needed by FIRST for the Year book page and will be needed for many other types of grant applications.