What systems are in place to ensure all sub contracts are being paid and no mechanics liens are being filed?

This far the mechanics of what he is doing are clear to me.

Check for cap ex coming, mechanicals, and smart repairs to do now that will save you later.

If no, are there photos of each unit and all closets, the basement, the roof, the exterior, and all mechanicals?

As an investment property owner, this means less maintenance and fewer unexpected expenses from storm related damage, often resulting in more affordable insurance premiums, less wear & tear on mechanical equipment, roofing materials or exterior surfaces.

If the building is currently recognized as a single family residence,  then you are changing use and presumably will need to sprinkler the building and satisfy other fire rating and STC rating requirements not to mention the added costs of having to run mechanicals for multiple units, multiple kitchens, additional bathrooms etc.  

Don I think what most investors miss with these funds is the lack of liquidity as in none until the investment cycles or the sponsor wants  to pay out.. the idea that folks can have a need for money after the investment and the Sponsor should pay it out upon demand only works if there is a mechanism in the offering to allow that.

This is coming from someone to stepped out of W2 in their early/mid 30s, and I can tell you first hand it's not cheap and anybody that tries this really does not understand the reality of it.To your other questions, cash flow is just a mechanism of leverage nothing less or more.

Their combined monthly income is 3X my rental amount but the man's income is in cash (he is a car mechanic).

I don't like mixing the two - it can get messy if he stops mowing due to mechanical or health issues, etc.