The Kendo UI Grid does not support your requirement
to show the cells of a row editable by default. This feature has been requested multiple times in the past, and, since it got so many votes
in the Feedback and Feature Request Portal, the developers took notice and developed a new control that allowed for this kind of functionality: the Kendo UI Spreadsheet.
I encourage you to evaluate the possibility of using the Kendo UI Spreadsheet instead of the Kendo UI Grid in your application; your second request, calculating the total sum of all the values of a row in the last cell of said row, is one of the most common uses of the Kendo UI Spreadsheet.
I hope this helps.
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