Milestones and Roadmap Diagram

Is there a way to extend the milestones beyond the range of the Roadmap diagram? Maybe with a circle or triangle at the end? Of course I can manually draw such an object, but it is not fixed in regard to reformatting the calender / diagram. That seems to be my real (and possibly rather basic) question: how to modify, enhance, connect and draw milestones so, that they move with the time axis while resizing the roadmap?

What do you think of milestones that work for only one of many partitions (may be nonsense in regard to the intention of the diagram)?

Is there a way to modify the automatic label of the roadmap (e.g. "CW nn" for "Calendar Week No. nn" without the year, or change the Order to "Year.Month")?