When involved in rentals, distance yourselves from your rental by using an LLC because it can protect you from frivolous law suits like slips and falls, damages in the units and catastrophic events like earth quakes, 100-500 year floods, fire and a list of other issues that may arise during ownership.If you hire an attorney, be careful, because most are after FEE's and can drag an LLC out for extra billing fee's!

Sorry about your Dad, maybe being aware of your time here on Earth with your kids was the gift he left you.

How on earth my 80% never got considered? 

Nothing earth shattering in it, but it does resonate with me - I have been starting to look out of state and no longer consider local properties to add to our business.

Tell your friend the cheapest way to live near the beach is near Kau, some lands are selling for 15k ;-) there're still abundant land even in place like hawaii, of course, living in county where there are only less than 33 people persqm maybe less interesting than hectic place like san diego lol i used to confuse when US gov. kept saying unaffordable housing, unaffordable housing means people that are living beyond their necessities, america is still the only country in the planet earth where it has vast land and income/mortgage ratio is lowest on planet earth.

He would be the stupidest GC on earth.

I do notice a couple of items here that would lead me more toward the water intrusion direction.1) Brick appears to be wet in some of the areas in the center of the first photo2) Foundation at the earth is covered by debris.

Most of them I have met were pretty nice and down to earth people, but I would be surprised if they would want to spend even 1-2 hours with someone new wanting info on tax sales. 

Generally speaking, new development projects will need to be at least 25K (or more square feet) in order to absorb the cost of land and earth work. 

All I would do is record my memorandum of contract, tell everyone that looks that there is a signed sales contract out there......then disappear off of the face of the earth for a while and make them come find me.