Change of parameter and colour legend seems partly coupled to the 3D view, partly not.

Yes, they are coupled. If one selects the profile first and the chooses a parameter, it will be displayed both on the profile section and on all surfaces visible. This is alike choosing a parameter for display without any surface selection. If a surface is selected and a parameter is chosen for display, then the profile section is updated to. In the case that multiple surfaces are displayed, the last surface chosen for property display will govern the property update on the profile section. An example: 3 surfaces and a profile are displayed. Nothing is selected and the parameter depth is chosen for display then all 4 geometric elements will display the depth parameter. Now, surface number 2 is selected and the dip parameter is chosen for display, then surface number 2 and the profile will show the dip parameter while depth values are displayed on the surface 1 and 3.