Payment finished from paypal

Hi,

I'm not sure that it will work but you can try to remove the line:
"return" => $return_url,
in the file plugins/hikashoppayment/paypal.php in order to not have the link. However, please note that the google analytics plugin won't work properly in that case.

Any message in HikaShop can be modified by overriding your translation file as explained there:
www.hikashop.com/en/download/languages.html#modify

I did not understand your question 1. Please explain again.

Usually, there is a "back to the shop" button. That helps a lot people who are not familiar with internet. Otherwise, they might think that their order is not finished and/or they won't know how to go back to the shop.
Most stores keep it.