Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.

There's a bunch of houses out there with "in law" units that make ADU conversions simple and affordable.

Keep the deposit towards additional rent if allowed by law and wish them the best of luck solving their problems. 

I am not lawyer, don't know much about law, that is what my understanding of what my lawyer told me. 

Your definition is correct for "legal non-conforming".The "legal" part of "non-conforming" is dropped when it doesn't apply so most commonly people call these units "non-conforming", "finished", "in-law suite/unit", or "bonus unit".Non-conforming: Any property that doesn't meet current zoning requirements.Legal non-conforming: A non-conforming property that was lawfully established under previous zoning regulations and is allowed to continue its use.Based on his posts @Mario Morales is referring to a non-conforming unit.

Unfortunately, Texas has a law prohibiting HELOCs on rental properties and I believe they also have a 70-75% max total loans allowed on the property which cuts into the equity I've built and would only allow for me to access 30K which would make it less appealing to go through the process for only 30K.

Hey,I’m transitioning from single-family to multi-family investments and looking for a comprehensive, practical course.

Some STR hosts have switched to MTR though with the laws so maybe you just have a supply problem there.

Let them come up with any laws all day.

I'd recommend starting by researching your local landlord/tenant laws and learning them inside and out.