The fact of the matter is, these properties don't exist for the datagrid. (As you, no doubt, have found out.) If you use the AutoGenerate property of the datagrid, the grid will have exactly the same amount of rows and columns as the datasource your binding to.
Even if you set AutoGenerate to false and manual setup your grid (using columns and ItemTemplates) you can not have any more columns then are returned by your datasource. Reference material for this can be found here:
"The one language all programmers understand is profanity."