I already responded to your second question in the support thread on the same topic. For the sake of other people that might stumble upon the same issue, I am quoting below the information provided in the ticket reply:
Binding the RadGrid control to a Sharepoint list is an unsupported scenario. If you insist on using RadGrid for that purpose you need to take the current/default View of the SP List, traverse its fields collection for the columns that are of interest to you, build a datatable or a collection of custom objects based on those fields and the data contained within and bind the datable/collection to the grid.
Hope it helps.
the Telerik team
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