I was told here and there that renting out a SFH that has keyed entry bedroom door knobs (standard single cylinder and turn-button on the other side) is a fire hazard and against some kind of code or, if not, makes you liable for fire hazard dangers. 

Find a duplex on the MLS that is a cosmetic fixer or fairly turn key.4.

You can't really wholesale something that is turn key or close to it.

I offered him $600 cash for keys if he was out in two weeks and the place was in the same condition. 

Back in the day, I'd have a prospective (residential) buyer come to my office and I'd qualify/interview them for at least 30--45 minutes before I'd even let them get into my car.Then with the advent of online MLS and all the Zillow's of the world, information is the key for a buyer. 

This is a key assumption to my problem so if that is incorrect please let me know.The excel formula of course uses the syntax IRR(values, guess)For this example:- Row 1 will hold yearly cash flow for years 1-5.- Row 3 will hold sale proceeds- I will sell the property in year 5 So it will look like this:A1= 100 (cash outflow)B1= 10C1= 15D1= 15E1= 15E3 = 25 (proceeds from sale of asset)Here is the formula I am using to calculate this=IRR((A1:E1,E3))This will return a value but I am not sure if it is the correct way to calculate this because I am not sure how Excel is interpreting these flows with regard to timing.

Are you looking for turn key houses to rent, or distressed/ fixer-uppers to buy low, renovate and rent out. 

I am interested in investing in the Florida Keys, particularly for short term rentals.

The key I got from you is that you bought and sold.  

The two keys for success are: 1.