Sub 30k houses are an absolute disaster with a tenant pool that will destroy your properties and make your life miserable.

A reserve is unnecessary, but I still keep around $15,000 - $20,000 in my account.The point is, that you should sit down and assess your finances to determine what the worst-case scenario may look like, how much you would need to cover it without impacting your life, and whether you will need to build a reserve.

Same answer whether you borrowed against your residence or against your rental A or against your life insurance or from your family or from any other source. 

I don't think those are bad things and sometimes the personal decision for your ideal life outweighs the "conventional hold forever" decision.You have options, that's the best place you can be.

Such a sad situation we are in, as their life's savings are at stake here... 

A cost segregation study is a strategic tax planning tool that separates the assets that have a shorter useful life and can be depreciated over 5, 7 and 15 years from the residential rental property or nonresidential real property that are depreciated over 27.5 and 39 years, respectively.

Whereas, you could be on the AG's hook for screwing John Doe the homeowner out of his sole possession in his life. 

Actually the IRS does not tell us what we can invest in, only what is disallowed (life insurance contracts and collectibles).Allowable investments for SDIRA investing include the following:Residential real estate, including: apartments, single family homes, and duplexesCommercial real estate Undeveloped or raw landREITs (Real Estate Investment Trusts)Real estate notes (mortgages and deeds of trusts)Promissory notes Private limited partnerships, limited liability companies, and C corporationsTax lien certificatesOil and gas investmentsPrivate stock offerings, private placementsJudgments/structured settlementsGold bullion Factoring investments

As long as the buyer prioritize lower monthly payments and is confident that they can manage the long-term cost of a 40-yr loan - If the buyer plans to stay in the property for a long time.Also, be sure to weigh these two drawbacks to a 40-year loan (paying significantly more interest over the life of the loan and building equity slower as compared to a shorter loan term).

If the tenant is truly struggling due to a life event, the sooner we can work together to get her somewhere she can afford (and not have an eviction or negative credit report on record), the better for all.