Hi Satish J,
1) RadComboBox has SelectedValue/SelectedValuePath properties
2) and 3) RadComboBox does not support sorting out of the box. If you are databinding the control and sorting the underlying collection, I guess it depends on the collection whether you will be able to insert an item at index of your choice.
4) Text property containing the text of the currently selected item, telerik:TextSearch.TextPath attached property to specify the member of the data item that contains the text value
5) The SelectedValue property is settable, it changes the selection of the control when set (you cannot set properties on the combo box items from RadComboBox)
6) The Text property is settable and changes the selection of RadComboBox
7) The same as #1
8) Not supported out of the box
9) Not supported out of the box
10) Not supported out of the box
11) Not supported out of the box
13) RadComboBox.Items.Clear() or clear the items of the underlying collection if the control is data-bound
14) Not supported out of the box. In data-bound mode it depends on the underlying collection
15) I am not sure that I understand this correctly, but I guess the answer is yes.
16) This is not supported currently, we have it in our plans for the future. The present version supports filtering, which will hide all items that does not start or contain (this is configurable) the entered text.
the Telerik team