Small things considered: 

    Screws, nails: How is the house put together?

Prior to the 1840's most screws were hand made (fig 1).  They were not tapered, and tips were blunt.  To avoid splitting the wood and get the screws in, predrilling was a necessity.  Slots were handmade with a chisel, and are often off-center.

Nails prior to xxxx were hand wrought (fig2).  After xxxx nails were cut as are modern masonry nails, but they were not tempered.  As a result, the builder could clinch (bend) them to fix the pieces in place if the back of the piece was available.  Early cut nails 

    Interior door locks: Who is locking out who?

Most of the locks in the house are of type know as Carpenter 60 rim locks (fig x).  They were patented in England in 1830 and obviously were imported after that time. Many of the houses in New Castle have this type of lock. What the locks tell us in our house is not only that English machined goods were readily available, but from which direction the protection was desired.  As shown in the house plan (fig y) with directional symbols:
           protected >| excluded
The users of the parlor, parlor and "living room", 2nd floor bedrooms, 2nd and 3rd floors all wished to be able to lock out others: presumably servants and tenants living in the back of the house.  

Cistern:  Is there enough water for bathing & cooking?

The dining room floor has a trap door to access a well or cistern (fig j). Removing the floor boards while installing air conditioning ...  The roof of the house is approximatley xxx square feet.  With the current annual rainfall of zz inches, we would expect an annual water supply of jj cubic feet or qq gallons.  If the cistern is 10 feet deep by 10 feet internal diameter, it would hold zz gallons.  The modern average water usage is bb gallons (ref).  After water from cooking is subtracted  much/not much water would be left for bathing.

     Stairs, ceiling heights, room size, finish: "polite" vs service areas
    Paint type and colors: what did the house actually look like then and over time
    Saw marks on timbers and joists: just how old is the "kitchen addition"?
    Fireplaces, cast iron stoves, heating methods