I only know about the times where this was found out prior to closing, obviously I have no way to know about the times this shady behavior wasn't found out.Since you get a vote in who this tenant is, and it's retail, PSA that commercial lenders (especially the ones offering the best terms...) are starting to vet deals by how 'recession proof' the tenants are, even if they are currently paying on time.

Would the goal after I get a duplex to use the income streams and my work income to pay it off as soon as possible?

The LLC business account pays the bills.

Let her keep paying the rent from the mother's estate if she needs to.

Portfolio lenders use more of a DSCR analysis to lending - meaning they are likely to lend to you as long as the investment can pay its debts - more so than a residential lender. 

You pay for the scrap pile. 

Some folks will argue properties are typically taxed less than their fair market value, and that may be true, but it's the amount of annual taxes your pay (regardless of actual value or assessment) that will affect your bottom line.Additionally, until the recent market correction both property values and rents have increased at a rapid rate.

Alternatively, you could work with an attorney or real estate agent to help and pay them a flat fee.6.

They wanted to make money, but they were focused on protecting downside risk.

That's less that what my father is paying on policies in Florida for a $400k home not anywhere near the ocean.