Which activities should go on my college applications?

Just put it all down, or the most you can fit. List them in descending order of importance for you. The things you are most proud of or worked the hardest on should always go first to advertise your own success. Dont worry so much about the essays on the application. Half the schools I applied too didnt even have essays. As long as your GPA is strong and you are involved you should be fine. More and more schools are disregarding SAT's now because there is no conclusive evidence that SAT scores foreshadow the caliber of the student in college.