Welcome to Greekchat!
I second what AXOeva has said. Definitely take advantage of this opportunity. If you can't meet with her in person ahead of time, I would call her so she can at least put a voice with your name - email and IM can be a bit impersonal.
Questions about the time commitment and colonization process are good. Also, ask about their philanthropy work. Talk a little bit about yourself, maybe mentioning some clubs you've been involved in (especially if you were/are in a leadership role) and/or some volunteer work you've done. You will go into more detail during your interview, but it's not wrong to mention it beforehand.
I'm also a chapter founder (although my situation was a little different - I was a member of a local sorority that became a chapter of AEPhi, so we didn't have individual interviews). It was a great experience creating something new and taking on a leadership role, and being able to establish new traditions.
Good luck!