To edit the url of the "contact button", you have to edit the view "product / show default", the url is in the code:
<div id="hikashop_product_contact_main" class="hikashop_product_contact_main">
<?php
$contact = $this->config->get('product_contact',0);
if (hikashop_level(1) && ($contact == 2 || ($contact == 1 && !empty ($this->element->product_contact)))) {
$empty = '';
$params = new HikaParameter($empty);
echo $this->cart->displayButton(JText :: _('CONTACT_US_FOR_INFO'), 'contact_us', $params, hikashop_completeLink('product&task=contact&cid=' . $this->row->product_id), 'window.location=\'' . hikashop_completeLink('product&task=contact&cid=' . $this->row->product_id) . '\';return false;');
}
?>
</div>