Remember Fannie uses debt-to-income (DTI) but the commercial loan uses debt service coverage ratio (DSCR). 

@Maria Marrero  Dept Service Coverage Ratio or DSCR for short, is the amount of Net Operating Income ( NOI ), which does not include your mortgage, Divided by Total Dept Service (TDS) ( usually mortgage payments, equity loans ) so the formula is: DSCR=NOI/TDS.

Mortgage with P and I, water, sewer, insurance, taxes, electric and such comes to $3569. 

That’s not taking anything out for tax, insurance, repairs, PM, vacancy like it should.

The way they insure this is by requiring you to purchase at least as much as you sell and to use all of the proceeds form the sale in the next purchases if you want to defer all tax. 

It’s very unlikely to have been related to the home’s systems, since it’s a brand-new house.I believe I have a handle on how to proceed, but I’d appreciate any advice on how to handle security deposits with regard to cause, and tips on dealing with insurance.  

Yes, this is true, a requirement from FHA which insured the loan, quite common.

And as your "insurance" file for eviction anyway so that when/if they don't move out on the agreed upon date, you at least have started the process instead of wasting a week or however long you gave them on the cash for keys deal.

The LTV requirement was met and the PMI has been removed from the payments which currently come in just shy of $1,000 a month for P&I, Insurance, and Taxes. 

Currently living at home to save money while paying for student loans, car note, car insurance and other bills.