I wouldn’t if I didn’t have to though, due to the opportunity for an education.Depending upon the profit that could be derived, you might just let them complete the property with the understanding that you want to minimally participate but understand every aspect of the project.

Figure out a return that you'd be comfortable earning for this project and its associated risks (see cap rate derivation explanations if you want to know the particulars of how to determine this) and make sure that you don't pay over that amount.

How does one derive valuation with such different noi's?

If you look at all the specialized products, they all contain a halogen derivative to kill mold - look at a periodice table of the elements and the second column from the right contains all the "-ine" compounds, chlorine, fluorine, astatine, etc.

Stated income should be consistent with income typically derived from the borrower’s occupation.

Personally, I like to be able to kick my investments, but it is not the only way (when I was in the securities industry I witnessed the birth of derivatives. 

When they do I remind them that they were happy with the profit they were making a minute ago - so why would you begrudge me a profit that I derived from great marketing and negotiating with sellers?

With that classification, the profits derived from sales (above the purchase price and rehab expenses) would be deemed to be ordinary income, subject to self-employment tax and ordinary income tax.Other factors weighed on this decision, not the least of which was the fact that the profits from sales of properties constituted the primary source of income for the taxpayer during the period.------------ TURBO TAX ---------------------Your issue is that "flipping" is capital gains.

Are their any exchanges where you can trade real estate derivatives to capture price variations outside the stock market? 

This assume your goal is to retire and be financially free.Of course, if you derive enough joy from that expense (coffee, or whatever) then this does not apply.