Postal thief drama 'Baker'

Emerson Baker, a baggage man on a Midwestern railroad, initially stole from parcel post packages using unlocked pouches. He later crafted a key at home to access first class letter mail, stealing currency from hundreds of pieces over several months.

Who was Emerson Baker and what was his occupation?

How did Baker initially steal from the parcel post packages?

What method did Baker use to gain access to first class letter mail?

Over what period did Baker manage to steal currency from the mail?

What was the total number of pieces from which Baker managed to steal currency?