However, it's important to carefully consider the rental market in the area where the duplex is located and make sure that rental income will be sufficient to cover your expenses.It may be helpful to consult with a financial advisor or real estate professional to get a better understanding of the risks and potential rewards involved.

On the same token, private money exist and you need to network a lot.

@Jay HinrichsRunning your investments as a business is essential- your point of having sufficient cash reserves, cash flow and being willing to make it through good and bad is crucial.  

But here's the thing with an FHA loan with either 3 or 4 units (duplexes are excluded from this), you must pass what is called a "Self Sufficiency Test."

@Stefan Demopoulos, as Jay said, the self-sufficiency test is the reason it wouldn't likely work in this interest rate environment.

I would keep it to two units as most 3-4 units right now don't pass a self sufficiency test and will require much more than 5% down.

Simple W9 should be sufficient 

While the attic distribution wire was sufficient for 30A, the feeder lines were not.  

If you have sufficient # of unit to where the cost of hiring a book-keeper is worth it, then yes, get one.

Having done a number of shower stall tile installs I am amazed that anyone would expect the paper coating on green board would be sufficient to absorb the thin-set to ensure the  adequate adherence of tile to a vertical surfaces vs that of cement board.