*2)* If a cell A references another cell B then cellA.Value will return the value of cellB
*3)* When inserting a DataTable ClosedXML will take the columns captions (if available) and use it as headers. If no caption is available then the column name will be used. Thanks to nitzzzu for the suggestion.
*4)* You can now set data validations to multiple ranges in one shot via .Ranges(...).DataValidation.