Assuming that you are interested in buy and hold, you will also need to include repairs, capital expenditures (CAPEX), vacancy, water/sewer (unless tenant is responsible), and property management.

Anyway, I always leave with the standard first step: Have you talked to a lender yet? 

I use Renters Warehouse for tenant screening and placement (I do the management), and use their standard lease. 

And while you're at it, check into Passive House building standards(google "passivhaus standards.") 

in our Charleston new builds and every new build I have seen there they all have tankless water heaters standard on the outside of the house.. in Oregon its an upgrade.the reason I was told in SC to have them is the water rusts out the ones with tanks so they leak and so that's why they want them out doors.. 

I would also recommend completing the rehab to the standard of the comps since that is what your loans will be based on and your rental base and buyer base will be expecting.

You will always have a mortgage payment eventually, pay interest, insurance, water/sewer, save for your reserves such as vacancies, cap ex, and repairs, and of course, can't forget property management if you are not planning to manage them yourself.

A couple things to consider:The infrastructure was designed to support a specific development (number of parcels, certain square footage and/or water consumption). 

There are many rental comps in the area- Wheaton Center and the towers should provide a good standard for market rent in downtown Wheaton. 

But something that you will need to know is that we are being told that a standard 20% down is not enough for a real estate investment property.