If I NEED to sell within five years, this calculation provides insight into the real-world return that incorporates these vital aspects of the investment.I want a balance between steady cash flow and long-term appreciation potential. 

Three days to replace a shower seems a bit long. 

Please recognize that you’re new to this, so don’t jump at the first shiny object to cross your path.

If a renter wants to extend for a few months their stay beyond the initial lease term, will I be a) required to extend and b) at the same rate as their existing rate?

He recently had a death in the family and is irritated that I won't give him time for to deal with that, but this has been a problem for long before the death and now he won't return my texts or answer my phone calls. 

As long as you are in your due diligence contingency you can back out with minimal expense.

Also for those with section 8 experience, how much work is usually needed to pass inspection, how long is the property usually vacant for and where can I find assistance for the steps along the way and all the paperwork.  

Are you looking to lead with long-term cash flow, equity growth, or maybe both?

Therefore the time frames don't align and presuming that people logically stop paying their taxes and mortgages at the same time, the Sheriff Sale would happen long before the Tax Sale. 

Quote from @Bradley Hendrix: That is a long post, but it's what people need to hear.