One problem I am having trouble with, (this is literally the last piece i am looking to add before I get more complex with what the spreadsheet spits out: taxes, market fluctuations, etc...) is the "Annualized Total Return" analysis on the BP calculator.

@Katlynn TeagueWe are not changing our strategy at all, while down slightly they will fluctuate for a while but do not see them going down significant factor for a long time

Prices of real estate fluctuate up and down but low-end rents (950-1200) are steady in any market good or bad in the Austin MSA.  

I would imagine the longer the better but I know it fluctuates sometimes depending on year of purchase and sale.

if someone were to buy a house hack or a rental property, how would he evaluate what neighborhood to buy in wrt the future re-sell potential of the house and the ability of prices to not fluctuate greatly with changing times?

Demand does fluctuate from the summer to winter months, but the data shows that the top properties still have high occupancy during the slowest parts of the year.

Because of the fluctuations in exchange rates during the remodel, it is difficult to ascertain exactly how much I spent in dollars.

I have smart pricing enabled, so the price automatically fluctuates within the range.

HELOCs will follow the Prime Rate, so your interest rate would fluctuate and you have to be OK with that.

The temperature fluctuates a lot in the spring and fall in the smokies.