A C-10 Electrical contractor can explain how to split the units, you may have to sub meter yourself.splitting a single unit in 2 is generally more complicated than building a common wall. 

That’s a complicated set of questions but it insures you get past every reason it would be taxable.

The simple answer is yes if you were using conventional, it gets complicated if you were to use FHA on your 2nd primary.

In order to do this, the law has to become complicated and convoluted. 

There just isn't much guidance available. asking for detailed answer for a complicated set up like this .

If the goal is increased equity and wealth then upgrade properties judiciously and increase rents or trade up using real estate exchanges.  

@John Dean, There's another complication with owner financing when you want to do a 1031 exchange. 

This will provide a definitive answer regarding the total square footage and ensure you base your decision on accurate data.It's important to verify all aspects of the property's description and measurements to avoid any surprises or complications later on.

However, with the more complicated operating systems and heavy competition, that’s not true anymore. 

Failure to inform your lender and insurance could lead to complications, including potential policy voiding or loan default.