There are many columns and I want to size the width of each column to the max. length of the largest value in each column.
For each column, that shouldn't wrap, set the ItemStyle wrap property to false.
<ItemStyle Wrap="False" />
Also if the data is numeric I want to left justify within the cell.
Again, you can use ItemStyle to style the column.
Do something like this:
<ItemStyle CssClass="alignRight" />