I was involved with mine a few years ago when I worked from home - unfortunately they hold their meetings on Wednesday mornings, so it's hard for those that work to attend. It was mostly made up of more "seasoned" women (

), and they loved having a younger alumna involved. I tried to get others involved, but it didn't work because of the timing of their meetings. We did look into trying to get a 'Junior Circle' going for the alumnae Panhellenic... tried to contact the groups' area reps for a contact. No luck...
Any NPC group alumna could attend the meetings, and elections were held annually. They tried to switch up the different groups who were represented on the board, but they basically had to take anyone who was interested. There were about 150 women on their roster, and 50 who attended the monthly meetings. They gave annual scholarships to high school students in the area, and held one fundraiser luncheon each year. I made some good contacts in the group, and just wish their meetings were 'working-woman-friendly' so I could've been more involved!
Good luck - and keep us posted if anyone finds out other information!