Hello,

Please add this code to the Theme Settings > Custom CSS > Global:

.woocommerce-table--order-details tfoot{
	display:none
}
.woocommerce-thankyou-order-details .total{
display:none;
}

As for the rewriting of stings, use the free Loco plugin. Loso > Plugins > Woocommerce and you will find the strings you mention.

Best Regards