It's probably safe to assume less risk with married couples since that is a longer process to end.I have several rentals that typically attract roommate scenarios, young professionals. 

You can purchase a property that you later convert into your primary residence after a year or two (there's actually a safe harbor from the IRS at two years). 

I know a few wholesalers that don’t bother to check if their numbers are on the DNC list, however I prefer to play it safe, avoid fines, and respect those individuals that signed up for the DNC option. 

If the structure is safe and no water is coming in then you could potentially wait.

The problem is with my credit of 680 the bank is saying they can not meet the safe harbor thresholds on any loan.

There may be some slick people on BP with a formula for you to calculate rehab cost, but to be safe you should really get a GC or two in there to assess the situation and provide you feedback on potential costs. 

My rentals tend to be C-Class (safe neighborhoods, but lower middle class), plus I'm in a soft rental market. 

How did you deal with lead certification, lead safe or lead free? 

Playing it safe is definitely best!

Upper Darby is safe to live ?