Ahh, Greek life... I never did Greek when I was in college, so I am by no means an expert; however, I will try my best to answer your questions and fill everyone in on the Greeks!
Greek "rush" for both girls and boys is simple, you choose one "house" that you want to "pledge" or belong to. You select this house because you feel some sort of connection to it. It could be that your mom or dad was in that house, it is of your religion (yes, they have Jewish, Christian & Muslim Greek Houses) they also have it by race or culture (Hispanic, Chinese & African American), or maybe your major or your likes in general.
However, once you select that house, you can only pledge and try to get into that house. If you don't make it, that's it. It's over and back to regular dorm life for you.
The Greeks do take a bad reputation here in the States in the press. We only hear about the negative side of them, when things go bad, each year students tragically die during rushes:
http://www.nytimes.com/2013/01/12/ny...nity.html?_r=0
listoflists
We never hear about the millions of dollars that they raise for charity:
2010 Sigma Chi Derby Days at Rutgers University raised over $95,000 for Children's Miracle Network and Pennsylvania State University's Dance Marathon raised over $12.3 million for Pediatric cancer, and Chi Omega chapters (girls) have, combined, raised approximately $2.3 million for the national Make-A-Wish Foundation.
The housing that the Greeks live in can be amazing though. We saw this one, the Chi Omega in Chapel Hill but couldn't take a photo as the traffic was too busy:
Also the lasting bonds, I know an older woman who is on the Board of Education who still has lunch with her "sisters" from her sorority.