I doubt 10% of the GRM will equal enough to where an S filing status makes sense.The home office and such is nominal so that alone isn’t worth doing this.

There's an equal chance they stay here and even a shot they go higher. 

Who is to say my dollar equals how many equity shares?

Well even if the rent is equal to the mortgage, you'll still be in the negative after repairs, CapEx, vacancy, etc.Why would you specifically be thinking of investing at a negative cash flow?

Many different partners equals many chances for litigation. 

Chances are this is NO deal property as the X will want their fair share and a fair market appraisal will need to be done and the equity split equally.   

If I have a problem with my newspaper delivery or something equally non-critical, I'd like an answer or fix  now, but if it's later today or tomorrow, not a big deal. 

Since the original mortgage stays in place, you only need to ensure the reinvestment equals or exceeds the proceeds.

You don't have to split it up equally in between purchases. 

I do want liquidity to invest elsewhere which is why I'd like the cash back from the reno ASAP, but I don't need liquidity equal to the value of the house--just the basement build-out, if possible.With option #3--how do you "cash out immediately"?