Windows in random rooms were covered in condensation with no clear explanation. 

Cost: What is a realistic cost-per-unit for getting a distressed C-class property up to the City's current point-of-sale/Certificate of Occupancy standards?

If its a working class or lower class area forget about it. 

I tell them things I have done, places I have invested, tactics for getting a better deal, ways to afford a better property, etc.

But they’ll need a proactive CPA who understands real estate — not a typical “file and forget” accountant; Rick I really hope this helps you help your friend, I sent you DM on BP, it's one of the reasons I do this, I hope you can assist. 

After knocking on doors for about a year, I got one of those calls you don’t forget: a seller wanted out of a 10,000 ft² commercial warehouse immediately.

They can choose between an agent-led showing or a self-guided tour.As the property owner, you can control the time windows during which the property is available for showings.

We use RentSpree and it's invaluable for getting detailed information and verification.

I have painted, fixed up, new ceiling fans, window dressings, etc. and it is move in ready.  

Don’t forget to join online communities like BiggerPockets, where you can learn from experienced investors and ask questions.Lastly, make sure to crunch the numbers carefully on each property (consider mortgage, taxes, repairs, vacancy, etc.) to see what kind of cash flow you can expect.