It is no different than if Dairy Queen released a "news article" saying study finds eating ice cream on hot days is great for preventing heat stroke. 

Additionally, rent control (and related restrictions) may prevent you from choosing the best tenant, limit your ability to increase rents to keep pace with inflation, and dramatically increase operational costs.Never invest in a high-crime city.

Duplexes will generally follow the same rules but on a bigger scale, such as minimum lot size, zoning restrictions, parking spaces, etc.As far as legal issues go in renting out a room of your home, Ive never heard of any jurisdiction that legally prevents you from having a roommate.

The LLC can act as a legal barrier to prevent liabilities for assets within the LLC from exposing assets outside of the LLC.

Does anyone have a rough idea about the cost of installing a back flow preventer in a five unit multifamily in San Diego?

If something went wrong, you didn't do enough to prevent it.It's a good book to shift your paradigm from " this happened because of some external factor" to "unknown external factors are always present and I need to try and account for as many of them as I can as best I can". 

Good pool of blue collar renters and probably better rent/price ratio than most main areas of DFW.Stay away from most new construction areas as the HOA can basically prevent landlord/renters or make life difficult with restrictions.

What are you missing that's preventing you from making your first purchase?

Generally, if you have a policy you can be assured that no issues will pop up later that will prevent you from selling it or refinancing it.  

It can be hard to win a failure to disclose case in a caveat emptor state unless you can prove fraud on behalf of the seller basically, that they covered it up preventing you from finding it during inspection.