I'm more asking about whether or not there needs to be a physical 5th unit or simply because the county assessor's website mentions 5 units, can that be used as a basis for the appraisal.

That happens when the option is exercised. 

Also negotiating with the owner a lease option so I don't have to come up with a huge down payment and I could choose to exercise the option in a few years or so. 

She’s also yelling same and threatening retribution and physical violence against anyone bidding at the sale.

ITs really an area that we physically go to the property to see where it is, and between my wife and I we drive in that area a dozen times a week.I believe Junius heights historic district is there (if not its a block or two away, same with Swiss avenue.)

What should I look for, besides a physical walk through, clean title, and the normal property purchase math?

If the property does have an occupant you (if you win the bid) are responsible for getting physical possession of the property, Auction.com does not facilitate this nor does the seller.

I am not used to trading, as my job is more into physics.

and then see what kind of property taxes the cities and states had.From the lists on the image attached, then I'd narrow it down to areas less prone to natural disasters.This was a small exercise I did, and I am sure people will agree and disagree with many of the places but hopefully, it's a starting point for a debate and we get more experienced investors to give us their two cents.

Tons of smokers, loitering, cussing in public, and even a couple situations that made the local news (tenant through a TV off the second-story balcony, then the next week drove his car into one of our contractors trucks and threatened him with physical violence...4 police cars on the scene).- New desirable tenants do not want to move into an apartment complex and pay market rents when it's still a dumpSo we accelerated the entire process.