Yes, automatic cycling is my suggestion. Your suggestion is “manual,” but it requires modifying the hotkeys and possibly the hovertext hints, both of which I consider to be part of the user interface. The code would also be more involved, as you have to do everything in my suggestion plus allow the user to define and interact with the parameters.
To me, the color of the marker is not important, but I would like each one to be a different color. I do understand this isn’t everyone’s use case, so I’m just voicing what I would find useful. Brian’s plan to make the colors easier to edit would be a step in the right direction for every use case, regardless.