Ah, I just played this game a few weeks ago.
For that jump, you want to wait for the board to tilt as far back/upward as possible, then run forward and jump just as you're hitting the end. If the board is too far down, she'll miss.
Also, for those flying banshee things, I use the cards--about 3-4 throws gets them, I think.
Later on in the game, the jacks are very effective, FYI.
The game does get rather frustrating. I save very often, every other minute or so, even less if I'm in a very hard platforming area.