Visualization Barplot vs Combo Chart

[buchberger_a]

Hi guys,

I'm kind of stuck. I want to have a perfect visualization and have therefore 3 questions:
 
1. In bar-charts i can show the segment labels, how can i do that in a combo-chart?

2. If I have several measurements, i can not label my Y-axis useful anymore. In the case of my appendix, it would be nice to show as label: "length [cm]" (If would have one dimension, I could do a work-around and rename the measurement in the data to "length")

3. I have added a line to the combo-chart but now the color of font is hard readable. Is it possible to fix that somehow?

I hope you can help me
Cheers
Alex