Well, since one of the things you mentioned is that your parents think your grades will slip you could mention the following...
Greek Letter Organizations (GLOs) have a minimum GPA requirement for membership. They all differ, but are above 2.0, the requirement does not stop after rush.
Generally the GPA requirement for someone to stay active in the chapter and be able to partake in all rights and priveliges is above a 2.5 (ours was 2.65) per semester. This does not mean that if you don't make grades you are out, but it does mean that you will probably lose some priveliges such as voting or attending non-mandantory events, and you will probably have to meet with the scholarship chair to discuss an action plan to bring your grades up.
In order for a chapter to stay active and have all rights and priveliges on campus the chapter as a whole must "make grades" meaning that the semester GPA for the chapter must AT LEAST meet the GPA of the all women's (for sororities) or all men's (for fraternities) average for the semester.
I don't have a statistic for philanthropy, but maybe someone can help. I would bet that as a whole greeks on college campuses do a majority of the community service percentage.
Hope some of this helps
