Hi,
You will have to edit the email "preload" part, so in the order_status_notification email, preload part you have to remove the PHP if condition:
if(bccomp($data->cart->order_discount_price,0,5)) {
don't forget to remove the ending bracket to avoid PHP error.
So that will display the shipping even if it is free.
Then for the subtotal issue, it should already display "sub total", please check the translation for the text key "SUBTOTAL",
I think that this is just a translation issue.
www.hikashop.com/support/faq.html#tran