Well, when I play stuff with a keyboard, I would expect dashes to be on SHIFT. But since the dash is also the only way to jump, making it SPACE would also be fine I think. I am not sure about about the bounce mode, since it is unique and you have to hold it - So I would most likely put that on SHIFT and jump with SPACE.
But then again, making them editable and/or using a controller might be the best solution (especially, if you plan on adding more mechanics)