x2 Questions - Tax and payment method!

Hi,

1.
The VAT is not displayed in the invoices unless there is tax to be applied.
It's a valid point to have the same behavior in the emails.
What you need to do for that is to change the line:
echo '<tr><td colspan="4" style="text-align:right">'.JText::sprintf('TOTAL_WITHOUT_VAT',$currencyHelper->format($data->cart->full_total->prices[0]->price_value,$data->order_currency_id)).'</td></tr>';
to:
if($data->cart->full_total->prices[0]->price_value!=$data->cart->full_total->prices[0]->price_value_with_tax) echo '<tr><td colspan="4" style="text-align:right">'.JText::sprintf('TOTAL_WITHOUT_VAT',$currencyHelper->format($data->cart->full_total->prices[0]->price_value,$data->order_currency_id)).'</td></tr>';
in the order creation and order status notification emails that you can edit via the menu System->Emails (Business edition only).
In your case, since you never want to display the VAT, you can even just remove that line so that it never displays.

For the Total with VAT text, you can use the language override system in order to change it:
www.hikashop.com/en/download/languages.html#modify

2.

For the payment information, you can it like below in the order admin notification:
<?php
$paymentClass = hikashop_get('class.payment');
$payment= $paymentClass->get($data->order_payment_id);
$payment->payment_params = unserialize($payment->payment_params);
echo 'Payment method: '.$payment->payment_name; ?>