1. The motor and headlight in each engine get connected to the power wire from the intake rollers and to a body ground;
2. The 2 wires between the engines connect the respective brush points?
Incorrect. There is no direct connection to the brushes between the diesels, only through the track for one brush and through the field coils for the other.
So there's no direct connection from the remaining E unit to the other engine's motor?
Incorrect, that is the only connection between the diesels... the two wires circled are wired directly to the reverse unit. The two loose ends of each pair of motor fields not connected to a brush on both motors are connected in (anti)parallel so they run in opposite directions. Parallel would have the A units in a tug-of-war if connected back-to-back.