For residential multifamily properties (1 - 4 units), can you use a home warranty to take care of the repair costs associated with rentals?

It would be a shame to rent it long term to someone who can lock in rent control at these depressed renal rates (and then never move out). 

Here's an article with things to consider when selecting a cost segregation company.

To save those costs, you might want to stick to some year build and older, for example, if you cannot do inspections on the properties that you are buying due to off-market deals or something else that is hindering you (all sellers I buy from do not want anyone in the home till we close).

We are in a constricted market cycle, low volume, strained budgets, high costs.

Here's an article with FAQs including the cost of a study.

It would be nice if you had a contact who was an actual mason not a marketer.  1930's construction is rare so maybe they cut some corners it was a global depression.  

The savings from either will be many times the cost of the lawyer.  

Also, what are some other low cost amenities that I can add to my STR that will yield a higher ROI?

Seems like it's in a lower end area so if it is filled you will have tenant issues and turnover cost.