Hi kaityln,
Rush is a great expirence especially for freshmen girls. I recomend coming with an open mind, and a positive attitude ( which can be hard after the 5th party in 100 degree weather)
Lexi has some excellent advice on the school specifics. When you go to orientation find the panhellic booth and ask any questions you have.
Also you and your roomie should try your best to get in different recruitment groups otherwise you'll be temped to pair up. which can hender you from getting the full effect of recruitment. Do not worry about going to different sororities. In fact it can actually improve your friendship because you'll both have new expirences to share with on another.
Although it is the sororities "job" to get the reference, it never hurts to come in prepared. find out the sororities at ECU and the ask your church ladies, school teachers, family members and in other communty connections for references... ie an alumnae panhellic council.
After you have done all that come to school get settled in and enjoy what could be one of the best expirences of your life. Worry about who you can see calling your family over the next four years!