As far as if something goes wrong on the job site, my understanding is that since the company I hired is insured they would pay for those damages / injuries.I hadn't thought about what happens 2 years down the road when tenants are in there and the house collapses and then I get sued and maybe my insurance policy doesn't want to pay because the changes I made were technically illegal. 

Not only will they debate it but the minute you get an agent who is also a member of the bar and decides to challenge this then your model begins to collapse. 

Remember the collapse of 2008?

He sent him off to rehab clinic, and the father was left with a house full of trash, and leaking roof that was so bad that the entire 2nd level drywall had collapsed. 

While I'm not saying that Oakland will overtake San Francisco anytime soon, I believe the population growth is big enough where Oakland is also seeing a portion of this growth.I am long bullish on Oakland and barring some crazy event where tech collapse and all tech professionals move out of the Bay Area, I think this will become a prime location.Feel free to PM me if you like to chat.

How quickly could the population of 25,000 collapse down to 15,000 or say 10,000?

Then a collapse will begin with widespread layoffs which will in turn affect housing.

Rents in many markets increased during the housing collapse.

Other than that, you are looking for signs of a leaking roof, or structural issues (bowing roofs, walls, collapsed foundation walls etc.)

At a 10% to 15% deductible, my buildings would have to sustain substantial damage or completely collapse before I saw anything from the insurance company.