I am simply asking for proper accounting and explanation to verify before I reimburse her. 

To address this, we agreed that I would work in the business for six months to verify the financials, which so far align with his POS system.My main issue is that at 23, I don't have strong financials to get a conventional loan at 75% LTV with a ~7% rate, and the seller's lack of financials complicates bank approval.

How do you find such information on lenders or anyone you want to verify legitimacy.  

This confers no insurance protections to the landlord, but what it will do is provide policy documents and the right to check on the policy to verify that it is in force.

Then from there you can call local PM's to get a better feel for market rents to verify your assumption for further due diligence 

You can find that document recorded at the county where the property is located, or you can search public notices (here's a link for Utah):https://www.utahlegals.com/(S(qz3suyqbucrgtawc2hx2bhv4))/def...Search 'foreclosures' in the dropdown menu.The Notice of Trustee's Sale will contain the "trustee" name, that is who represents the lender in the proceedings and you can contact to verify the case is still active.

The city will require a few pictures of the apartment to make sure it is live-able and once a lease is signed and submitted to HRA, they will verify the applicants income, and it will take up to 10 business days for NYC HRA to write a check for the total amount of the 1 year lease. 

The house next door is identical in structure and is also a Duplex, however, I have not verified that.

Verify all permits for add ons.7.  

Verifying last 2 years of rental history very important!