point 1
i comment out my images
example: themes / niara / category.tpl
<!--
{if $subcategory.id_image}
<a href="{$link->getCategoryLink($subcategory.id_category, $subcategory.link_rewrite)|escape:'html':'UTF-8'}"
title="{$subcategory.name|escape:'html':'UTF-8'}">
<img class="replace-2x img-responsive"
src="{Link::getGenericImageLink(
'categories',
$subcategory.id_image,
'medium',
(ImageManager::retinaSupport()) ? '2x' : ''
)|escape:'htmlall':'UTF-8'}"
alt="{$subcategory.name|escape:'html':'UTF-8'}"
title="{$subcategory.name|escape:'html':'UTF-8'}"
width="{getWidthSize|intval type='medium'}"
height="{getHeightSize|intval type='medium'}"
>
</a>
{/if}
-->
second point i dont know - its disabled on my store
i think blockcategories modul