You can achieve this by following our online demo with source code provided. It demonstrated an integration of RadChart and RadTooltip. The approach will be absolutely the same for Pie series. Let me know if you need further assistance with this.
As for your second question - could you please download the latest binaries of RadHTMLChart. This way you'll get RadHtmlChart control in DotnetNuke 6.2 version.
I would reccomend that you wait for our official SP release which is expected at the end of this week. There are plenty new features that will come alive and I believe you will find them very useful.
All the best,
the Telerik team
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