I'm in the process of learning the "right" way to calculate ARV and repair costs as well.

All of their college costs are saved for. 

When you look at your insurance policy you will see that the replacement cost of the duplex is around $450,000.

Closing costs to refinance run thousands of dollars.

So the Pro membership does not include everything the lower cost memberships offer?

It costs $300 a year in MD to maintain an LLC. 

Also, the opportunity cost of leaving the property vacant for a year while paying a mortgage on it and not receiving rental income is much higher than what the marginal difference in rate will cost you until you cashout refi it.

Is this estimate in your opinion low?

The Columbus market is known for it's strong appreciation factor, low taxes, and also because it is a land-lord friendly state.

You need to factor the cost of refinance (average $7K which may change depending upon the price of your home)