@Donald Hlava start by asking for a rent roll showing the rents for each unit, how many units are occupied and what the rental history has been.

I am looking into buying a house that can be owner occupied while renting out other parts (ADU, duplex/tri).

I am looking into buying a house that can be owner occupied while renting out other parts (ADU, duplex/tri).

If they are not owner occupied, you’ll be putting 25% down. 5% down is only for owner occupied. 

I have one occupied property and my personal house currently. 

I became an accidental Landlord in 2016 when I got an assignment to Misawa Japan 5 months after I closed on my first home.

The reason being you could use your 121 exclusion before it expires (2 occupied of last 5 years owned).

It's 3/4 occupied and I'm not sure if I need to have rental agreements for the tenants in place today or tomorrow.

When using an FHA loan to buy an SFH that requires owner occupies the rental for the first year, does anyone know if you can instead rent to an immediate family member for the first year?

Your best bet though if you're looking at those types of opportunities will be to research properties that are owner-occupied and their business is struggling and/or are delinquent in taxes, mortgages, and other liens.