1. In order to add the column in the Pivot Chart view you will need to use the same value for column Name and column DataMember property. In your case, the Name and DataMember will be co2

WebGridColumn col3 = new WebGridColumn();
col3.Name = "co2";
col3.Caption = "Contact";
col3.DataMember = "co2";
col3.Bound = true;

WebGrid1.RootTable.Columns.Add(col3);

2. This issue has been enhanced in WebGrid 7. I have reported this bug for WebGrid 6. I will inform you if there is any update / progress regarding this issue.

3. I could not replicate this issue in our environment. The image is displayed correctly. Have you make sure that you have already used the latest build for WebGrid 6 and WebUI Framework, the latest build is build 218 and build 705.

I just been updated for issue #2, unfortunately WebGrid 6 support is dropped so in order to have the fix you will need to use WebGrid 7.