The update isnt just bug fixes, it contains content for the Necro as well.
When you get in game it downloads the character for those able to get it.
And Correct, the Season Pass gives the 4 Campaign DLCs when they are released, not Gaige.
[Edited by DigitalIP, 10/9/2012 4:36:38 PM]
FYI - I do believe the correct term is MECHROmancer