Luckily, this could be simplified by estimating 3% of the purchasing price and 4% of the sales price for closing costs and then of course the real estate commission, which is 6% of the sales price.Moving on, we almost had the house under contract within the first couple weeks of having it on the market.

This is a very simplified explaination.

Paying in advance doesn't give anyone special privileges, it just simplifies the process. 

State regulations make things complicated so I'm skeptical that it will ever replace the agent; however, technology is taking the place of so much human production that it wouldn't surprise me to see some platforms simplify the process for the even the casual browser.I looked for the app for my Android, but only T-Rex apps displayed.  

Does he over-simplify and gloss over important details?

Yes but if you want to simplify your life a little, you could setup one of your series llc as a management company that receives all rents and makes all payments.

I've used simplified spreadsheets over the years and have altered them after finding and understanding things like cap rate, GRM, and a plethora of other RE goodies.Two years ago I realized I needed an income producing strategy for retirement.

But Let's just simplify it: your IRR is 8.44% based solely on an annual rent of 36k.  

On residential vs. commercial (simplified):1-4 dwelling units is considered non-commercial, which basically means that the borrower's personal income is used to qualify for a loan.

Without over simplifying, a note is a promise to pay.