I'm evaluating the RightEdge 2008 Edition. It is found that this verions has implemented a number drawings for charts. I would recommended that some markers (e.g. Dots, Diamond, Symbols ...etc ) should be implemented as drawings for coming version.
Marker is quite useful as it doesn't occupy much space on the chart and can give information without showing label with long wordings
I've had some luck implementing dot/symbol markers using the ChartCircle class and the ChartText class. For Dots, simply create a circle with a very small radius. For Symbols, I've been creating ChartText and setting the font to something in the Winding family. For symbols that can't be represented by a font/character combination there is also the ChartImage class.
As for more information tied to the object: I've looked into creating custom object properties (through derivation and/or encapsulation) that would display in the RightEdge property, but have had no luck yet. So it seems that labels are the only way to go here.