ADA Title III is the parent to all the derivatives of what is and isn't OK. 

@Wade KulesaI believe Dave Ramsey's 10 year number is derived from the common real estate cycle, as 10 years is the time to complete a real estate cycle. 

What's the expected financial benefit you hope to derive by going through this effort if the answer is yes to all of questions 1-5? 

It's also a reason I like having more money in hard assets like houses than cash and derivatives.

More specifically, I'm looking at entering into an agreement with a contractor where their fee will be 50% of the net income derived from the property. 

Did he/she assemble land sale comparables to make a market-derived adjustment, or did the appraiser just throw a dart at a land adjustment on the Land Adjustment Dart Board?

So as long as one is not overleveraged in relation to the income derived from that asset (= leaving enough room for a positive cash flow factoring in vacancy and other nuisances when speaking of real estate) and has some cash reserves, leveraging is not a problem.The problem we saw in  around 2008 with leverage on the private side is that people completely overleveraged.

This Addendum to Purchase Contract is entered into and is effective as of ___/___/___ by and between Seller(s) and Buyer(s) (hereinafter referred to as “the Parties”) and shall be deemed to amend, modify and supplement that certain Contract dated ___/___/___ by and between Seller(s) and Buyer(s) (the “Purchase Contract”).NOW, THEREFORE, in consideration of the mutual benefits to be derived from this Short Sale Purchase Contract Addendum and of the representations, warranties, conditions and promises hereinafter acknowledged, Sellers and Buyers hereby agree as follows:1.

From these properties, you can derive what I call a property profile.

I made an auto-populating spreadsheet that I derived from the four-square worksheet, and I'm happy to share it with the BiggerPockets community.