Utilize tools like BiggerPockets for resources and calculators, and consider creating a simple spreadsheet to track property details, budgets, and timelines.

Then separately I calculated the appreciation against each home value observation in the ZHVI dataset against its value 10 years earlier for each month.

You are best off to raise the rent and give the tenant the option to stay.Also, I hear a lot on here that "rents should be", "the potential rents are"... make sure that you do your due diligence when calculating potential rents because most new owner OVER estimate them.

So for every million dollar in equity you'll get about $60,000 in net cash flow.Play around with a BP calculator, plug in a million worth of RE with 20% down and see what happens over time.

If you are planning on living there (ie in 1 unit) then you are house-hacking and this is a different calculation consideration then renting out both units and making it a true investment.

As its interest is actually calculated daily.

SDE is calculated by taking the net income and then adding back certain expenses, such as the owner’s salary and non-cash expenses like depreciation and amortization.

That being said, anything can happen, but if you run your numbers accordingly, make sure that your contractor is trusted and do all the other stuff you'll be a little more protected than the next person flipping that does not do this type of calculation. 

Many times their cash flow calculation is using flawed underwriting.  

BiggerPockets also has a calculator to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.