If you double click the thumbnail photo, it will download the full size image.
The "Pass Original Query String" checkbox is not a part of the Data Assist wizard.
After the pages have been created by the wizard, open the insert page. Go to the server behaviors panel (Window -> Server Behaviors).
In the Server Behaviors list, double click the Insert Record Server behavior.
The "Pass Original Query String" checkbox is a part of the Insert record server behavior, it is also available in the Update Record Server behavior.
