Just go to the ones that are currently for rent and look at the rental history.

The basic history of the home to the best of my ability is, 1 home was purchased in 2001 then sold again in 2004.

Which is based on your income.Concerning 4 unit duplex  you can us 75 percent of the rent income towards qualification for a VA loan if you can show you have a history of renting on your tax forms.

Look at comp history. 

History does not repeat itself....but it does rhyme.You won't be able to recognize a market peak when it happens, nor a market bottom, even if you are a savant. 

If you choose to get inspections on each ask the inspector for a discount if you give them 10 or 20 at a time.Does seller have actual/completed maintenance and capex history broken out per property?  

Perhaps you can evict for other reasons as he also has a history of evictions and repossessions.

I'm from eastern NC and I believe its the perfect place for multi family RE.

The reason why most landlords look between 600-650 is because most renters don't have a history of mortgage payments to boost their score.

Even with HML, I've applied in the past and most pull credit, they told me not so much for score, but to check if you have Bk's, foreclosures, liens, or a history of settling debt for less than agreed.Certainly there are owner finance deals where it might not matter as much, but personally, I believe in the RE game, good credit helps a lot.