I've never modified any file solely for the PHP-version. At least not if it is supposed to be working, which in your case it should since it's PHP 7.0 and PS 1.6.1.11. You sure all the other settings for your store is up to date?
Yes. At least 7. If you want to run 7.1 you need to add this fix so you wont have the spinning icons in BO.
https://github.com/PrestaShop/PrestaShop/pull/7392/files
You probably need to alter the path to the image in the right *.tpl file in the paypal module folder. Located somewhere under view/front (or something). If you rightclick and check the path of the no-image file, you'll notice that the path is wrong
Have you tried taking a SEO-check on both addresses to see how they do? Just search for "SEO-checker" in Google and go through the first page or something.