On the subject of colours - the RadHtmlChart uses a different skinning mechanism than the rest of the RadControls, so for the time being you would need to use its built-in skins and colours or create the items programmatically so you can choose their colours, as you have discovered.
On the subject of tooltips and labels - currently this functionality is not available. We are considering extending this functionality and once it is finalized and released information about it will be available in the release notes.
the Telerik team
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