Comments won't submit

Can you give a screenshot of the vote tab of your configuration ?

That's because you removed the username field:
www.hikashop.com/en/forum/4-how-to/49492...roduct-comments.html
Since that field is required for the javascript, it breaks the javascript when you submit the comment.

you would have to change the line:
var pseudo_comment = document.getElementById("pseudo_comment").value;

to:
var pseudo_comment = document.getElementById("pseudo_comment");
if(pseudo_comment ) var pseudo_comment = document.getElementById("pseudo_comment").value;

in the file administrator/components/com_hikashop/classes/vote.php

Yes, edit the file "show_default" of the view "product" via the menu Display->Views and add it after the line:
<div id="hikashop_product_vote_form" class="hikashop_product_vote_form">