The REO stigma is a measurable value that banks recognize as a discount seen in the market once a lender has taken the property back. 

What are some added security measures that you have or have heard of someone putting in their contracts?

(There is an acronym which I learned it is called SMART which means: Specific, Measurable, Attainable, Realistic, Timely) Look it up.3. 

The fema requirements forFlood zones are stringent and when areas flood the entire neighborhood takes a hit in values and takes a bit to rebound.

I can install Google Analytics to measure how much traffic my website is generating, which allows me to then install a code for retargetting ads that will follow that site visitor.

You should be allowed to have your contractor do a walkthrough and at least measure and estimate for this worst case scenario so you can determine if its still worth the effort.

Contracts with deadlines with positive and negative measures for finishing early or late

To piggy back off sticking with 4 units or less which will allow you to put less money down for a residential loan vs commercial loan there are added benefits when it comes to cash on cash returns - which in my opinion is a great way to measure an investment. 

So far I've read Frank Gallinelli's book - What Every Real Estate Investor Needs To Know About Cash Flow...And 36 Other Key Financial Measure, and Brandon Turner's book The Book on Investing in Real Estate with No and low Money Down. 

Bucket with canvas tool holder liner w/ compartments for hand toolsTape measurePhone: for photo's of measurements of or any type of object weather a plumbing part or screw. and to use  as last resort to call someone else to help :)