It uses the standard dreamweaver recordset and recordset interactions. This is a setting in the dreamweaver repeat region server behavior that can be updated through the existing DW user interface.
Giving user options of the number of rows from a form is not directly supported, but should be very easy to do if you have a rudimentary knowledge of forms and php. It should just be a matter of updating a variable to come from a session and then creating a form to update that session with the number of rows.