Seems you misread the Season Pass.
It clearly states only the 4 DLC add-ons: Captain Scarlett, Mr. Torgue, Sir Hammerlock, Tiny Tina and the UVHP.
If you pre-ordered the game, you get a Premiere Club DLC pack which included some of the others.
Just Steam. For consoles, Amazon.com.
SE: We have some awesome summer savings on our games, excluding Final Fantasy.
Eat Lead: The Return of Matt Hazard.
If you mean storywise..it is set after Trails in the Sky and before Cold Steel...or maybe at the same time as CS now that I think about it.