Landlord residing in basement that lacks kitchen & shower

[Svend W.]

I'm considering purchasing a 2 flat property in a suburb of Chicago but the timing isn't great for the family to move--I would rather not pull our child out of middle school during the last year--so I'm wondering if there are any limitations on me making the basement my legal residence while the family continues to live elsewhere. 

The basement is finished and has a toilet and sink, but no shower or kitchen. It has a carpeted floor, 2 means of egress, a normal-height ceiling and a good-sized normal window in the front room and a glass block windows elsewhere.

Are there likely to be any limitations on a landlord choosing to make in such a basement their legal residence? And could it be shared with a tenant (e.g., just one room reserved for me)?

Thanks in advance.