I dont think the jurisdiction would want the shared driveway coming from the back permanently if the road is planned to be developed.Just  my thoughts!

Interesting math problem.You may need to normalize the appreciation in any area vs others, because the biggest factor for appreciation is going to be related to the printing of money in Washington DC.It appears to me you are missing the most important variables related to supply and demand:Jobs within X milesPopulation growthHousing startsI could see how a flood zone could impact appreciation, but race seems an odd factor to include over supply / demand drivers.

Are their other items (bad debt, write offs, etc..) that might impact your net revenue number?

The "times" will impact all deals all the time, depending on the "times". 

It is much less of an impact when you go from 3 beds to 4 and even less from 4-5.

As mentioned above, if you were to secure a blanket loan on the 4 rentals (either rate/term or cash-out refi), it would remove your existing lienholders, place the new loan into a DSCR loan which does not impact your DTI, and subsequently reduce your personal DTI at the same time.Then, continue to scale with DSCR loans.

The reason the water levels are going down are not because of Vegas, though that doesn't mean Vegas can't/won't be impacted. 

Overuse impacts everyone.  

Market conditions in terms of construction style and it's impact on ease of ductwork install as well as level of competition among vendors in your area will affect your pricing.  

At least if it goes to a collection agency it is more likely to haunt the tenant over the years as it will impact his credit history.