Do it incorrectly and a gas leak can certainly be dangerous. 

Imagine she gets audited and it's determine basis was incorrectly calculated and she owes money.

This is also incorrect, at least partially.

those with knowledge are often addressing other newbie advice that was incorrect, those that jump on basic stuff are often those thinking they know but never really studied RE from the beginning (because it's seen as not providing any cash return for their effort). 3.

They will know their personality quirks and hot buttons.  

Just listened today of some lady who had acquired 150 properties within 8 years, so I don't know what I'm doing wrong or incorrectly.  

I never stated that, so you are assuming incorrectly.

If you don't subtract the cleaning costs out of your gross revenue (like many people don't do) that's incorrect.

I would highly recommend making a list of house rules and general info (WiFi info, trash day, and info about any quirks in the home).

It wouldn't be expensive to just pay for a quick consult and I would think the peace of mind (and avoiding the possibility and liability of handling the situation incorrectly) would make it money well spent.