Become familiar with what the 6 ADU/JADU regulations allow and their limitations. 

The reason this is important is that it implies that duplexes purchased will be under rent control regulations (assuming a unit is occupied) regardless of if the new owner decides to move in (house hack) after purchasing the property. 

Recently there have been municipalities that have set guidelines (regulations) that prohibit denying a tenant for previous criminal convictions at least x-years ago. 

Regulations.

Obtaining knowledge of foreclosure laws will be helpful as they regulate the rights of both borrowers and lenders in the event a borrower fails to uphold his or her end of a mortgage agreement.

if you have a large group of investors then you should make sure that you are in compliance with SEC regulations.

File a complaint with whatever agency in your state regulates mortgage originators (presuming this person is licensed or registered, which you can check on the NMLS Consumer site).

I know based on IRS rules I can't get the same benefits as the funds, but I can still invest the funds capital as long as I abide by all regulations.

You won't believe how expensive they can get to build and then there are a lot regulations that go with them as well.

If you want the definitive answer on CA ADU regulations email ADU @ the HCD domain (BP does not allow email addresses but you can figure out).