A few thoughts:- Regarding the estoppel certificates = I'd get the completed/signed certificates before the final walk-through so if there's any discrepancies or issues you have plenty of time to resolve them before closing

If your goal is to accumulate properties it would probably be better to stick to the 30-year to preserve room in your debt-to-income ratio for future acquisitions.

He shares my concerns about the insurance, capital reserves, resale issues, etc.  

If the market dives when you are halfway through a flip that is taking 2 years when you thought it would take 6 months you could have an issue on your hands when trying to resell.  

Chicago has had a lot of issues  and they seem to be getting worse.

I know the issues and we are addressing the issues. 

One issue you'll likely run into is even getting conventional financing in the first place.

He also told me the fly infestation were bottle flies and were a sanitation issue.

The two biggest variables are condition of the condo to begin with (ie. if it is old, it's more likely going to have more maintenance issues) and the quality of the tenant that's in place.

Also - " Smile , Keep Eye Contact, (no sun glasses), keep your hands and arms open, turn a quarter or half turn so your back is to the front door as it opens, (Smile and stretch your arms out open in your car just before you knock), stay positive, always be closing for appointment, set appointment for future date, get phone # and cell #, bring paperwork to appointment, ask questions as to what is the most important issue with selling this home, craft your pitch around this answer, close deal, repeat process for next deal "Door Knocking in a nut shell ...You will strike out say 9 out 10 times, so what?!