I did write an essay with my secondary but that is not necessary. You just need to apply before school starts (and ideally the summer) because there are limited spaces. In terms of opportunities, I am particularly fond of Spanish opportunities. The track provides funding to take Spanish classes. I am also currently writing this from Nicaragua as part of a CUUNITE sponsored trip to learn Spanish and help out a little bit in the community. I got a stipend for this but I understand the grant expires after this year so future grants are uncertain. We are offered loans from the university for the summer though.
Just as a whole, the track provides a great understanding of the needs and resources for the underserved. The other tracks are also fantastic and I encourage you to look into those as well since you can only join one.