Finally, how can I estimate the costs for repairs?

Junked it out, cleaned up landscaping, drywall repair, texture, paint, new interior doors and trim, new waterheater, new floors in kitchen. some new floors, countertops, new roof, painting cabinets.

My concerns is how should I handle and dealth with the temants when they become very demanding in terms of fix/repair things. 

So maybe you negotiate those repairs into the deal to avoid that?

Added piers in foundation, repaired electrical issues.

The school spent $275,000 on repairs, improvements, made paymemts for 6 years, and paid us off.  

leases.The only work I think it immediately needs is fixing the back steps and a few roof repairs.

Too many headaches for cash flow on paper (which is actually negative in reality) : stolen AC unit (thieves climbed a 7 ft fence), attempted break in (alarm scared intruder away), repair issues, winter weather (make sure someone turns up the heat on a vacant property).

DSCR just has higher rates and if you overestimate the rents and underestimate the repairs or maintenance, the deal goes south quickly.

Compare how you would expect this home to perform as a rental with reasonable assumptions about cap ex, vacancy, repair etc and then figure out what kind of rental or possibly RENTALS (multiple) you could purchase if you sold this property and how would they perform.