The rehab was completed in Mar 1984, and after several failed attempts to sell, including a sale to a buyer in July 1984, and then the buyer got a mortgage approved, then loss his job, then the mortgage company rescinded the mortgage approval.

Put your grandfather's 1970s strategies aside during this time unique time in history where we're likely going to see a good, steady increase in values over the next 7 to 10 yrs, which can dwarf monthly deficiencies.PLUS, those deficiencies accumulate in what's called a PALA (Passive Activity Loss Account) which can be written off for years and even after the home is sold correct?

Some flat-fee brokers use the entry-only listings as loss-leaders to capture more lucrative full-service listings when the sellers, who thought they could do it themselves, give up. 

I made a loss on all three deals because of rookie mistakes.

Do investors deploy cash into a loss making property to turn it profitable and cash out...ORThey just take the loss and invest the cash elsewhere to profit against that loss?

a correction is occurring right now, big losses the past few weeks.

So your insurance company has $6,000 and it takes some of that money and buys "reinsurance" against excessive loss.

This is my understanding regarding taxes and vacation properties:1) If you rent it out all year long: You can claim tax and mortgage interest deductions, rental cost deductions, and rental loss deductions. 2) If you use it as a vacation home for more than 14 days per year and also rent it out more than 14 days per year: You can claim tax and mortgage interest deductions, you can claim rental cost deduction (but not over rental income amount) and you CANNOT claim rental loss deductions. 3) If you use it as a vacation home for more than 14 days per year and also rent it out for only 14 days or less per year: You can claim tax and mortgage interest deductions, you CANNOT claim rental cost deductions BUT that rental income is not taxed, you CANNOT claim rental loss deductions. 4) If you use it ONLY as vacation home and do not rent it out: You can claim tax and mortgage interest deductions (can only be done if this is your only second home...you can't claim this on unlimited second homes), you would have not rental cost deductions to claim and you would have not rental loss deductions to claim. 

When done I print out a detailed Profit & Loss report, and then put those numbers into Turbotax (Home & Business).  

For hazard coverage, many investors only carry actual-cash-value policies which payout a specified amount of cash in the case of a loss in order to protect the total investment.