Hi Jim,
I looked around briefly and haven't found any places where I'm using the IsRequired property on the DatePickerControl, so I'm not confident it works.
I know in the Blog/EditPost.aspx page I'm using a separate required field validator for the begin date and it works there.
Not sure about the issue you're seeing with presentation of the control. Are you testing/debugging it from within the mojoportal web project?
columns and maxlength are not valid properties, I would remove that.
Hope it helps,
Joe