spring rush for sororites

It depends how low your GPA is exactly. If panhellenic advises you to wait until spring, it would probably be a good idea. GPA is a very strong factor when it comes down to what chapters you will be invited back to. Spring rush is SUPER laid back, but not ALL chapters participate. You can always try spring rush and if you don't find a chapter that fits, you can wait and rush summer 2014.

If a chapter makes their quota do they usually participate in spring rush? Which chapters typically participate in spring rush?

It really just depends! Let's say chapter total is 200 members. So if a chapter has exactly 200 members and some members quit for various reasons, transfer, etc. this will allow for them to participate in COR (spring rush). The chapters that participated in spring COR last year were AOPi, ADPi, Alpha Chi, Gamma Phi, Phi Mu, Kappa, and Tri Delt I believe. But this does not mean these same chapters will be open next spring nor does it mean some others won't participate! There's no certain way to tell.

Most participating because of girls leaving for professional school, etc. will only be taking a very few. Likely they already know who they want by Oct.

Your options in fall recruitment and spring cor will be the same. Top houses do not take sophomores. ΑΧΟ ΑΔΠ ΡΜ ΚΚΓ ΓΦΒ ΑΟΠ all took girls during continuous open recruitment. KKG only had a select spots and you usually need a girl pulling for you to get in. Just being honest, pi phi theta KKG chi o will cut you first day for being sophomore unless you have a great reason and have a girl pulling for you along with a great
Resume and personality.