Copying product misses some fields

That's indeed the case.

change the line:
$this->fields = array('product_weight','product_description','product_meta_description','product_tax_id','product_vendor_id','product_manufacturer_id','product_url','product_keywords','product_weight_unit','product_dimension_unit','product_width','product_length','product_height','product_max_per_order');


to:
$this->fields = array('product_weight','product_description','product_meta_description','product_tax_id','product_vendor_id','product_manufacturer_id','product_url','product_keywords','product_weight_unit','product_dimension_unit','product_width','product_length','product_height','product_max_per_order','product_min_per_order');

in the file administrator/components/com_hikashop/helper/import.php and that will fix that.