Does acrobat and/or flying make a character immune to trap card damage and effects, i.e. spike pit trap card?
Not as such, no.
At best, an acrobat/flier will be able to walk out of a pit without paying extra, or walk through a rubble instead of around.
You need to remember to differentiate between the trap card and the obstacle that the trap leaves behind after it is sprung. Acrobats and fliers are immune to the effects of the obstacles left behind, they are not immune to the effects of the traps cards as they are sprung. Which means that the traps affect them fully, until everything on the card has been completed.