Correct, that’s the case with the output curve function, the battery remaining calculations, the stick expo, they’re all [0,1] or [-1,1].
Your calculations and plot look fine, would give a good example in the documentation. A value of 0.75 can well be since in principle the turning speed of the propeller gives you quadratic thrust so if your ESC controls rpm and you neglect other less significant effects it should be nearly quadratic (value of 1). A lot of ESCs out there don’t control rpm but rather voltage duty cycle and/or do some internal half way linearization. That’s why it’s best if you do the measurements like you did and set the correct parameter 
I would really like to support thrust parameters and output with physical units in the future but it’s not there yet and not strictly necessary for good performance.