The Anatomy of Metal Type.

7
A term not labelled on this diagram is the kern, the part of the face which extends over the side of the type body and rests on the shoulder of the type next to it, or on a special, high piece of spacing material.
Kerns are often found on the letters f and j, among others.
f-kern
The pin mark was an indentation originally made by a feature of the mold used on the earliest type casting machines.
With improved casters the indentation wasn’t functionally needed, but the mark was sometimes kept to identify the foundry that made the letters.
One point is about 1/72 of an inch. (.0138″)
A pica is 12 points. (.1660″)
Type high = .918”
via Setting Type By Hand – Letterpress Commons.