Most of these houses were built over a hundred years ago and they are in rough shape. 

I did well over a hundred of them.So I would say 70% stopped paying within 3 months and then you just have to evict.but like others I had some go for a few years..

One hundred dollars per month might not do the trick, as the city is becoming increasingly hard on landlords.

There are literally hundreds of posts and blogs on bigger pockets addressing this topic.

My husband is experienced in hundreds of rehabs.

If you believe this is not sufficient, you can get an umbrella with an additional $1M (or more) in coverage for a few hundred bucks extra.  

I figured for a couple of hundred dollars, it might 'make' them a lot more if your estimate of the home's value is right. 

FYI--the hundreds of inquiries is normal in this area.

Totally understand that being a landlord is work, I've owned a real estate brokerages in Chicago that focus on residential leasing ( yep, that's a thing in Chicago) I've worked with hundreds of owners and property managers over here and my brokerages has rented 15,000+ units over the years.

There are literally hundreds of these, probably thousands in Cook.