Can someone explain how to evaluate if a multi family is a deal or not without having access to the historical financial data?

Before moving forward with the property, you want to at least see historical financials (ask for the trailing 12 month financials, rent roll, and anything else the seller is willing to share).

As an update, I received a copy of the rental license from the seller which in addition to historical zoning approval, confirms that the zoning is correct for its intended use as a duplex.

His grandson gives the historical account that it has railroad rails in the foundation. 

So of your two concerns one is historically inaccurate. 

If I were to take a property located in historic downtown Marysville (on B st around 2nd, 3rd, 4th St) and rent by the room to personnel serving at Beale Air Force Base, how likely is there to be interest or demand from someone serving at Beale? 

@Ricky StaffordUse historical median price table from here.

The 2-2 story homes are next door to each other in the historic district of this city, and 1 has been completely gutted already; the other has been separated into 3 different units, and has 1 tenant still in there upstairs, and the two bottom units have been trashed.   

Also for rehabs, what software do you use to track expenses related to type of work completed (electrical, plumbing, etc), and what features have been important to you in your business to analyze historical expenses on rehabs?

REIAs historically are where experienced folks hang, the older experienced types.