Purchase price: $186,000 Cash invested: $46,500 Home was built in 2018 as a long term Section 8 rental unit.

A 100k home in Podunk Oklahoma that was built in the 1930's, is going to probably need a whole lot more than 10% of rent going towards capex, and likewise a 1m home in San Francisco isn't going to need anywhere near 10% of rent for capex. 

I have an opportunity to buy a property in tennessee that has 25 self storage units AND allows for 25 more to be built. 

It sounds like you have a solid foundation and clear goals for your first multi-family investment.

I wish we had this mechanism up here in the NW It would allow many more projects to get built.

I'm looking for a 10-20 unit, built after 1960, needs repairs and the unit mix are 1 bed and 2 bed because most people don't rent out 3 bed.

My name is Bernice Retzloff and I am the in house realtor at Foundation Property Management in Memphis, TN.Investing in Memphis, TN could be a great move for you, especially if you're looking for positive cash flow.

I agree with @Jonathan Greene here that the first step is thinking through what to do with the primary residence - you might try this tool that I built a few months ago to analyze whether you should keep or sell the primary residence! 

Apps built for long term rentals, like RentRedi, won't help you manage bookings from Airbnb and VRBO.

3) When was the property built and remodeled?