Contacted by McKinsey BTO Recruiter

I applied online for a Business Technology position few days back and recently got contacted by an Experienced Hire Recruiter at McKinsey BTO.

We spent a couple of minutes talking specifically about BTO (what it is/what it isn't), the life of a McKinsey Consultant, etc, etc. He then told me he would schedule another interview with me next week to "discuss my background specifically".

I haven't been through any consulting recruitment process yet, but from what I understand all McKinsey recruiting is case-based, following a Problem Solving Test. The Recruiter didn't mention the test, but he did mention the case interviews.

First, I'm sort of surprised why I was contacted to begin with. I have no consulting experience, although I do have BS/MS in engineering and one year abroad fellowship consulting for non-profit. I was number 1 in my MS class (Ivy) and my fellowship was also with another Ivy (but still research/engineering), not business related.

Second, if this is an Experienced Hire position, would that mean I would join as a Junior Associate vs. Business Analyst?

Finally, the recruiter mentioned that he "serves" particular offices. Does this mean he just refers candidates to offices to begin recruitment process or does this mean that my next interview with him is the first round?

Thanks for the help.