A solid agent can help you calculate ARV, manage inspections and contractor connections— get quotes and coordinate handymen and vendors post close, provide shopping lists and software suggestions for management or STR furnishing, etc. 

It's worth looking at a blended rate calculator before you make a final decision of the type of loan as it will show the new "blended rate" of your HELOC and first mortgage if you go that route.

All the BP calculators I've seen are based on LTRs. 

I’ve even had structural engineers say that a deck or other structure should have fallen down as well, according to their calculations.

There are several websites available today that will help you to calculate potential rents.

Narrow your focus, stop buying properties, and figure out what you actually know really well rather than letting FOMO, spreadsheet calculations on faulty pro formas, and advice of strangers on the internet influence your investment decisions. 

The 1% rule is a simple rule which is easy to calculate and describe. 

I do have my VA disability as my "job" income and I hear that lenders will count that at 1.25% for calculating DTI since it's tax free.

Calculate expected returns, costs, time commitment, etc.  

Taking into account home prices and interest rates in 2024, that added cost today would be between $1,800 and $2,800 per year for a typical mortgage holder, Zandi told CNN after updating his original paper’s calculations.