Hi,
1. and 3. That "white field" is not a field. It's empty space.
Change :
.hikashop_checkout_cart td.hikashop_cart_product_name_value {width: 64%}
to:
.hikashop_checkout_cart td.hikashop_cart_product_name_value {width: 100%}
in the frontend custom CSS of Hikashop in your HikaShop configuration and it will fill the whole space there.
2. If you don't want the white background there, you can add custom CSS like this:
.hikashop_cart_product_quantity_value .hikashop_product_quantity_field {
background-color: transparent;
}