I would consider putting SOME money down if you've got savings Doing this would improve your DTI for future purposes and improve your cash flow and equity performance.

We have inventory throughout Southwest Florida including Cape Coral.

The price range you're looking at for 2-flats in the area is definitely on the lower end so you should be prepared for some work but what you described is a lot more problematic than making some cosmetic improvements.

A good tenant is someone who:Has stable employment in a market segment that is very likely to be stable or improve over timeHas a credit history with which you can evaluate the likelihood that they will performPays all the rent on scheduleTakes care of the propertyDoes not cause problems with neighborsDoes not engage in illegal activities while on the propertyStays for many yearsGood tenants are the exception, not the norm.

There may be some local factors (nearby construction development or major change) influencing the owner to sell at a discount OR perhaps the owner has not been keeping up with capital improvements and the tenant base as suffered and therefore actual collections of rent have been impacted.

I’m trying to buy a home from my in-laws and there selling the home to me for 100k the house value is worth at least 200-250k or more, and I plan on making improvements. 

My lot is worth $580k and the "improvements" are listed as...$1000.

Something I found odd is the calculator's projected cash flow seems to improve over time.

Since taking possession of the property, we have made significant upgrades to the property and improving the value of the property and making the building more aesthetically appealing to the neighborhood.

It's not a total piece of crap, but it certainly has a lot of room to improve the value given the market that it is in.