Hello,
Our theme and Revolution slider fully support PHP 7.3 and even PHP 7.4.
Don’t think that issue is related to the PHP version. I think that issue could be related to ModSecurity that prevents saving too long requests to DB or something. Did they ask your Dashboard access to check the request and check the server error logs that appear while they click on the preview button? We can just give you refund from our side, we can’t change the server settings. This is something that your hosting support should resolve.
Also, we would be grateful if we don’t mix all the issues into one topic. Create separate topics for different issues to avoid misunderstanding.
What error do you get while trying to edit links? Provide us with screenshot, please. You need to make layer visible first and then edit it. Hide it again after that if you need. You can’t edit the hidden layer.
1) Choose the portfolio page to fix the issue with the breadcrumbs https://prnt.sc/xb829b If the portfolio page is not set then the first project featured image appears in the project breadcrumbs.
2) The same. Set the portfolio page.
3) Logo height proportionally changes if you change the logo width using options https://prnt.sc/xb8c2q
Min height of the header you can set in the main/bottom/top headers settings https://prnt.sc/xb88y7
Header won’t be smaller than header content. Breadcrumbs paddings you can manage here https://prnt.sc/xb8ews Breadcrumbs won’t be smaller than breadcrumbs height + paddings.
Regards