Lenders are mostly interested in that you keep up with mortgage payments. There are lots of families that look for homes with a mother-in-law apartment to rent out to friends or family. If you are buying, you can only use rental income if there is history of rent at a property, which is almost always duplexes and multifamily.
In this economy, more and more people are sharing costs and 'overhead.' As long as your renter keeps in line with the culture of the neighborhood and isn't a nuisance, it shouldn't be a problem. Minneapolis codes require a legal egress window in case of fire. If there isn't one, you can usually enlarge an existing window without too much difficulty.