Hi,
1. Then configure a menu item that you set to a menu not displayed on your frontend, enable the carousel only for that menu item and provide the link to that menu item. That way, we'll be able to look at the carousel and no one else will see it on your website.
2. You're looking at the Display>Views menu of HikaShop.
But you need to look at the System>Configuration menu of HikaShop. There, you have a Display tab with a CSS section where you'll find the frontend CSS option I was talking about.
3. Yes, this is ok. As I said, you just want to disable the HikaShop group plugin via the Joomla plugins manager.
4. Yes, if you rename cart.php and with the "add to cart legacy" setting deactivated, that should work properly.
5. Just after you do point 2 and set the default CSS. You can edit it and add that CSS code at the bottom of the CSS file and save the edit popup and the whole configuration.php That will change the frontend CSS to "custom2" and that will it will use the latest CSS of HikaShop 4 plus that piece of CSS to fix the problem.
7. Well, I don't know how you configured the jQuery Easy plugin so I don't know what you did wrong.
However, if I look at your website with the developer tools of my browser and look at the head tag elements, I see this:
monosnap.com/file/hEboxYjKaT0kda8edfLXJYp9qPVGfR
Normally, with jQuery Easy, instead of /media/jui/js/jquery.min.js I should see a jquery URL from the
code.jquery.com/jquery/
page or from google
ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
or something like that.