Closed sales within 90 days are given preference, and must be within 180 days.

My basic assumption is that I must consider the premium on a rental property above zillow's estimate price as the "rehab" cost in the Rental Property Calculator.   

a) Buyer must pay off the loan before acquiring the property? 

You must must must take action

My question is are we allowed to enter the property if they don't leave and don't consent to a visit?

You must be talking about how to attract motivated sellers that want to sell. 

I couldn’t agree more, we must be grateful everyday for life itself.

Look for a new market, run the current numbers for currently used markets, and rerun the numbers for previously eliminated markets...to see if they are still out of the picture.Situations change, markets change, so you must follow the changes and adjust.

I recently went to visit my niece who lives in the city of Detroit. 

Include in that a visit to see for yourself, and make sure you are working with a property management that has an excellent record.