setting the stroke width of way borders and way points?

way borders are to thick, waypoints are to thin. There are some hidden settings for that?

do you mean the graphical representation of these in the editor?

Yes, I mean the lines in the editor

I agree that the way borders are too thick. You can change the colors of the way point lines & nodes via the editor options > colors section. You can't change the size of them, but if you zoom into the scene they will be much easier to see, select, & draw, etc.