When Jesse, Tulip and Cassidy are researching the Saint of Killers, several pages and cover illustrations from the "Preacher: The Saint of Killers" comic mini-series are shown.
A Sokosha is a small tank or heavily armored vehicle.
In the library, some pages of the original Preacher comic book by Ennis and Dillon are shown.
After listening to the Saint of Killers Tape, right before Tulip stops the Tape we hear the narrator say Dick Cheney would be discussed in the next chapter of American psychpoaths. Cheney was the Vice President of the United States under George W. Bush. He is known for supporting the "enhanced interrogation techniques"- program and has also been compared to Darth Vader by the public.
The writing on the armored truck reads translated something like "happiness soul number number". While there is a clear connection to the company's true business, the symbols seem to have picked without actual knowledge of Japanese, as the phrase is not really meaningful.