I was curious what legal grounds I have to their offer since their notice clearly states the price they are asking for.

A lot of our forms are just to keep us organized and save us time and are not legal in any way.

Are there resources I can look up to see if i can wait and enact new leases that include tenant paying utilties and what legal issues I may encounter there?

Even if it isn't specifically stated, there have to be some catch alls in your lease that gives you legal footing to evict the drug user. 

Does anyone in Chicago know the legalities around this?

Are there any legal reasons not to go with this approach? 

info about the property19% Cap Rate 35 out of 75 are occupied150 to 175 rent per monthPurchase price is 250K for 75 spaces.Thanks in advance for whatever guidance and info you all could share.

@Michael Weis - some lenders will actually get you as much as 80% depending on the loan program and whether it is recourse (i.e. you personally co-sign for the loan to your legal entity) or non-recourse. 

Are there any legal ramifications for running a business of that sort from a single family home? 

Hello Everyone My name is Shawn and I hope to one day become real estate investor here in Atlanta an also hoping to get some help and guidance along the way.