Hi Mitch! I would suggest you check out Craig's List to see what is going on for rents in the areas you are considering a purchase. I have owned a duplex rental property in Minneapolis since 2003, and Craig's List has been a great source of rental rate info and tenants.
I learned a lot about being a landlord prior to ever becoming a license real estate agent. I would also suggest you check out the City of Minneapolis website for information on the City's rental inspection and licensing process, vacant building registration fees, special assessments, "conversion" fees for buying previously homesteaded property and "converting" them to full rental status (this fee was $1,000 a year or so ago - that may have changed) and if you haven't ever owned rental property before - consider taking some classes.
Here is a link to the City's website: http://www.minneapolismn.gov/index.htm
Under the "most requested" tab on the front page of the City's website, you'll find a link to Property Information that is very helpful in researching specific properties. Good luck in your search!