1) For file upload to function correctly, your forms encoding type must be set to multip[art/form-data.
change:
<form action="products_Insert.php" method="post" name="WADAInsertForm" id="WADAInsertForm">
to:
<form action="products_Insert.php" method="post" enctype="multipart/form-data" name="WADAInsertForm" id="WADAInsertForm">
2) The manage relational table behavior needs t have a relating selection in place. Select the element you would like to repeat to create the relation, and go to the Server Behaviors Window. click the plus button and select DataAssist -> Repeat Selection.