Is is possible to add a link to some products of my choosing on the category page like in this image - i want it to only show for some products and should link to my free shipping terms and conditions .
It would probably require some custom code in the product template file you have choosen.
It will be using one of a few files depending on what layout you choose in the admin; Settings > Appearance; “Product detailed page layout”
For example, my file path is; skins\MY_SKIN\customer\blocks\product_templates\modern_template.tpl
You would need some code in there that says; “if free shipping is active for this product, show the following text”
That’s more or less the logic of it as i understand it, I just can’t code it for you I’m sorry. 
You can add a products block on Design > Blocks > Categories
add into file skins/[SKIN_NAME]/customer/addons/my_changes/hooks/products/product_multicolumns_list.post.tpl```php
{*** added by HungryWeb.net ***}
{if $product.free_shipping == ‘Y’}
{$lang.free_shipping}
{/if}
{*** end ***}
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[ Tested on cs-cart v.3.0.6 professional ]<br />
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I hope that helps,<br />
<br />
---<br />
Valentin