Any additional advice for this newbie is welcome.

Since I want to be consistent and keep marketing to the first 1000 leads, plus the additional 500 new leads every 30-60 days, my DM volume would keep increasing over time eventually pushing into my marketing budget.

Any additional advice/warnings much welcome!!

Situation is resolved going forward and you provided the tenant with some useful information which you might want to include in future "welcome" packets to prevent this going forward.Just make sure to frame this as you are not at fault or implying responsibility.

Additional things to consider are things like led pipes and broilers.

If the investor on your loan participates in HAFA, you would have automatically been asked to fill the additional HAFA qualification documents.

Once you find what the zoning is you can look up the zoning code and read rules on additional dwelling units.

The property looks in pretty good shape and using conservative estimates on rent/expenses is should give around 11%+ cash on cash return and according to Zillow's Zestimate would provide an additional $20k in equity (I'm not too hopeful for that as Zillow seems pretty unreliable for pricing).

Assuming they are month to month, you could start a new agreement the following month to cover the additional cost of the unit at say $100 extra lot rent.

With the new lending rules, banks have been even more aggressive when asking for additional paperwork to support large deposits.