Septic, well, treatment of both, roads, water and septic lines, hydro, home pads etc.

Is there a difference in tax treatment of either?

the loan proceeds are traced to determine tax treatment and potential deductiblity.

I decided to experiment on myself and was successful and able to walk again after 2-3 weeks of self treatment using diuretics and laying down and sleeping after 4pm to elevate my legs to help reduce the severe edema.

You don't want to drop below the IRS minimum interest, but paying them principal vs. interest means the seller gets better tax treatment. 

Dad was sick with Cancer and passed on.

RRYou should verify this but,Yes - there will still be tax depreciation recapture for her if a note is taken back, plus the recapture amount is not eligible for installment sale treatment (i.e., assuming she takes back a note and at least some of the sale proceeds are received after the year of sale), so she would have to recognize the entire recapture amount in the year of sale and pay tax on it regardless of whether she takes back a note or not.The remainder of the gain (i.e., above the depreciation recapture amount), if any, should be eligible for installment reporting.  

I rip out the stinky carpet and renovate the house including a roof, termite treatment, and all new flooring and appliances. $15,000 later, I have a really nice house that rents for $800 per month.

@Darren Looker There are several factors to consider in order to fully assess the various approaches.SDIRA vs Solo 401k: Solo 401k can be used by those with self-employment income and no full time employees (other than a spouse) and benefit from more favorable tax treatment than SDIRAsWhat is your current marginal tax rate and how does that compare to expectations about the future?

The second gives you both tax deferred treatment in a 1031.