Labor: Eliminate Federal Student Loan Financing for college degrees with no or low ROI.

If the LLC is not an option with the realtor business (eliminates S-Corp election option) then I don’t think it is worth setting something up for investment purposes assuming you don’t already have a large RE portfolio.As for your other question, for most of my business owner clients I recommend using Interactive Brokers because interest earned on just cash (not putting it in any financial instrument or security) earns a very competitive rate relative to the many alternatives.

If you can get protection on the downside and you have to sell unexpectedly, then you can reduce or even eliminate your loss. 

Or is there a way to structure to eliminate any impact of the existing seller?

If you don't have much capital your best best is going to be house hacking a single family and eliminating your living expense.

The fact that with a Texas series LLC you can file ONE tax return for every sub LLC in the series combined, and operate out of ONE bank account, eliminates almost all of the “hassle” of utilizing a series LLC vs one regular LLC into which you place many properties.  

To achieve this, you need a passive income that meets two requirements:Rents must outpace inflation: If rents do not outpace inflation, no matter how many properties you own, you cannot achieve financial freedom due to inflation continuously eroding purchasing power.Income persistence: Financial freedom requires that your income lasts throughout your life.Whether rents outpace inflation and how long the income lasts depends on the city where you invest.Start with an initial list of potential cities and then eliminate any city that does not meet additional criteria.

The mortgages and closing expense can be written off to eliminate the taxes as you want 

Of course the time and monetary commitment would eliminate this from serious consideration for many people.  

We just walk away thinking, well we just eliminated some of the competition today.