Not going to change the world but since I'm not betting the farm I am ok with a little risk. 

Deja vu from 2005-2007..........Yes, you need to leverage your equity to keep moving forward....wont argue that....but to pull out ALL your equity to go buy more properties in a very high market, sounds like a huge gamble to me..... use the leverage....hell yes.....but using ALL of your equity is a huge ALL IN bet..... you better be able to back it up if there is a big correction......Guess I'm just a wimp.....hope you are right.......

It has a list of names and then columns for D.O.D and D.O.PI'm guessing D.O.D stands for date of death and D.O.P stands for date of probate.

Broker, direct mail etc.Direct marketing / cold calling is always a good bet, in the commercial world if you get a hold of a building owner in a principle-to-principle setting you can generally have some good conversations and suss out if there is an opportunity or not. 

Build it on excel is the best bet... you can adjust it for use in the future

Your best bet would be to do a tear off of the existing roof, inspect the wood planking for rot then re shingle it.

Gentrification is a powerful thing and having seen it up front, I wouldn't bet against it. 

With the current tax proposals, if you purchased a property with a large loan the interest may not all be deductible however renting is one of the worst things you can do from a tax perspective.Given the information you have posted and past experience I suspect that your best bet would be to structure a 1031 exchange on your property with the greatest appreciation, exchange it for a property that you want to live in, and move in after a period of time. 

The bet offer we can find through a bank is 30 years at 4% interest with 25% down.

My company will go down to a 580 min. credit score on FHA.I bet with some homework, you can finance it now and then figure out how to do the rehab?