Interior Demo in Chicago - Insurance/Permit?

[Chris Scales]

Hi all! I hope I'm posting to the correct forum... I recently purchased a 2 flat in Chicago that is in need of a full gut rehab. Between the basement, first floor, and second floor, there is about 2,500 sq ft of finished space within the property (mix of plaster, drywall, hardwood floor, carpet, tile, etc.) including 2 kitchens and 3 bathrooms - all of which will need interior demo down to the studs. I have placed the property under my LLC and of course have property insurance. I see on Chicago's Department of Transportation website that I can pretty easily obtain a 30 day dumpster permit for $100. This brings me to my questions regarding interior demo:

1. 1. What risks do I run into by hiring an uninsured demo crew to perform the work? What if they also aren't licensed? If I am getting liability waivers signed by each of the workers, does this provide me with sufficient protection in the event that one of the workers were to be injured on the job site?
2. 2. Do I need a building permit in addition to the dumpster permit in order to have the interior demo done? 

Thanks in advance for any help you can provide!