Is it possible to get one (balance) or two (equal power incl. width) pots instead of the slider?
2nd: Is it possible to lower the alpha of the measure lines? Like to 50% to just get the idea of their position, but don’t let them disturb the overview?
1) no. unless you want to reimplement the panners.
2) this link shows you the names of the colors in the theme used by the stereo panner: https://github.com/Ardour/ardour/blob/master/gtk2_ardour/stereo_panner.cc#L674 You can definitely reset the colors from the Ardour GUI itself; changing the alpha is a bit trickier and likely requires editing the color theme file for the theme you use.
No, I like potentiometers instead of sliders. Quicker overview for my eyes/brain. Like these:
Logic / Mixbus / Reaper:
When I compare big sessions in Ardour to others, I need much more time to get a quick panning overview. Here some Screenshots JUST AS EXAMPLES. Sorry for big pictures.