Parts diagram display/changing the category listing fields

Ok, Ive reset all the files and im going to try again. I've got a very important question though. By changing the Weight table to say msrp will that effect my database if i decided to transfer to another zen cart?

Also, I want to be able to have pictures displayed in one category and not displayed in parts category. Would I be able to get this effect by having a piece of code that hides the picture if not used? If that works, how would I do that? I'm assuming that I will be editing the same file.

Any ideas?

Well I got it to work correctly except on the product listing page. Here is the linK

I followed all the steps with a clean file. It works in the admin section. It just doesnt display in the tables on the category page.

What am I doing wrong?

product_listing.php

 case 'PRODUCT_LIST_QUANTITY':
        $lc_align = 'right';
        $lc_text = $listing->fields['products_ref'];
        break;

default_filter.php

/ We are asked to show only specific category
      $listing_sql = "select " . $select_column_list . " p.products_id, p.products_type, p.products_ref, p.master_categories_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, pd.products_description, IF(s.status = 1, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status = 1, s.specials_new_products_price, p.products_price) as final_price, p.products_sort_order, p.product_is_call, p.product_is_always_free_shipping, p.products_qty_box_status
      from " . TABLE_PRODUCTS . " p left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id, " .
      TABLE_PRODUCTS_DESCRIPTION . " pd, " .
      TABLE_MANUFACTURERS . " m, " .
      TABLE_PRODUCTS_TO_CATEGORIES . " p2c
      where p.products_status = 1
        and p.manufacturers_id = m.manufacturers_id
        and m.manufacturers_id = '" . (int)$_GET['filter_id'] . "'
        and p.products_id = p2c.products_id
        and pd.products_id = p2c.products_id
        and pd.language_id = '" . (int)$_SESSION['languages_id'] . "'
        and p2c.categories_id = '" . (int)$current_category_id . "'" .
        $alpha_sort;
    } else {