With investment properties, any kind of rentals, I often see the story where the owner walks away due to some major repair issue, like a caving in basement or maybe a string of awful tenants drove them away, but in either case, its NOT AT ALL because there's no way they can continue to pay the mortgage payments, its a financial decision and many times may be the best one they have available at the time!

. - Maintenance & Repair: 5% of total rent- Cap ex / utilities: 5% of total rent- Property management: 8~10% of total rent- Misc & reserve: 5% of total rentFull rent: 4800(rent) - 2600(PI) - 800(TI) - 1150(Expense) = $250/mOwner occupied: 3600(rent) - 2600(PI) - 800(TI) - 1150(Expense) = -$950/mOwner occupied & no PM: 3600(rent) - 2600(PI) - 800(TI) - 700(Expense) = -$400/m I thought it would be $0/m if owner occupied although $400/m for myfamily is low enough.

Then make sure you have sufficient reserves for emergency repairs.

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?

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

Added piers in foundation, repaired electrical issues.

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).