For Category, Manufacturer, Supplier, New products, Top sellers and Specials pages edit /themes/prestashop/product-list.tpl
1) In line number* 31, add id="pla_block_{$product.id_product|intval}" to the <li> tag.
Before: <li class="ajax_block_product...
After: <li id="pla_block_{$product.id_product|intval}" class="ajax_block_product...
2) Add <div class="pla_attributes"></div> where you would like the attribute drop-downs to be displayed.
In the example below, the drop-down menus are added on line number* 48, above the "Add to cart" button.
Before:
{if ($product.id_product_attribute == 0 || ...
    {if ($product.allow_oosp || ...
After:
{if ($product.id_product_attribute == 0 || ...
    <div class="pla_attributes"></div>
    {if ($product.allow_oosp || ...
3) In line number* 47, remove && $product.minimal_quantity != 1 if it's there (to enable display when the is a minimum quantity to order).