Man, you are asking about things that happened four years ago...during my drunken Sigma Chi days...I'll try and do my best.
I don't remember how long it took to get an interview invite. I seem to remember that I interviewed at SDSU during my spring break at NDSU, so that's the right time frame. I think I had my acceptance letter from NDSU by Easter...?
I remember having a nice chat with the dean, and then a one-on-one interview in a faculty member's lab/office. Then a tour, a bragfest about their APhA chapter, a handshake, and goodbye. Maybe a 2 hour process??? Overall, it seemed pretty laid back-more of a "get-to-know-you" than a grilling.
For the interview, prepare like any other. Suits are a must at this level (though I think I got away with a sportcoat). Know your strengths/weaknesses, and be able to showcase your leadership skills through your outside activities. I'm sorry, I jut can't remember anything specific from the interview other than the snow was melting, and my buddy was still driving a wrecker for a company there and he was doing it with a suspended license.
I don't think that the U of M gives overt preference to their students, but I wouldn't be surprised if it was there during the sorting process. Thought that the U of M was going to require a BS before admissions starting soon-like a year or two. Something to check into.
Is moving an option for you? If so, I could speak to the residency requirement for NDSU. With all A's and a C+, you'd be pretty competitive there (heck, I'd think you'd be competitive at the U of M, but I'm basing my judgement on what I knew back then. My fiancee got into the U of M COP then with a 3.3...I'm sure things are tougher now at both schools.)
I understand why ND and SD place residency bonuses in their admissions. Both schools positively bleed pharmacists into Mpls. Actually, about a 4th of my class is from the metro, or just outside it. With the whole rural pharmacy situation on shaky ground, the reasoning is that if you grew up there, you'll stay there. Its a poor solution to the problem, but minds won't change anytime soon.
Let me know if you have anything else I can help you with.