Every jurisdiction will be a little different but of course they all must follow state and federal guidelines.

You would need to buy a single one and get very lucky - at that point it's more like gambling.

I know quite a few people in Tech and they are all concerned with how funding is slowing down and quiet layoffs.In the past, it was really easy to raise money for startups because there were so many new millionaires willing to financially gamble on ideas.

I know once I go through this once and know a guideline, I'll have way more confidence and be able to do it again. 

A better description, rather than "lease audit", is "lease file audit" because in addition to the above comparison you are also reviewing the rest of each tenant's lease file to ensure that they were properly screened, don't have felony convictions (or were even checked for that), have proven income that meets your guidelines, etc.

My script would look something like this - "Our contract has clear guidelines for payment timing, and I'd like to adhere to that.

As to the mortgage requirement, all residential mortgages made under secondary market guidelines or under federal agency requirements will use 12 month residency as your initial intent for your loan application, your EBO may or may not, but my guess is they would also. 

You could be onto a great deal, but make sure your sitting pretty without having to raise the rents, because if you have to raise rents to make it work, your gambling!

So if you have greater than 4 you need a lender that can work directly under one guideline or the other, not both or you will be limited to 4 mortgaged properties to cash out refinance.  

Generally (check with your local guidelines) property boundary law works as such: that your property line extends "down to the center, and up to infinity".