Hello,
1) Theme Options > WooCommerce > Single product builder > Breadcrumbs https://prnt.sc/2699fhv
2) We used the built-in template on the demo. But you use a Single product builder and it does not have the option to change the order of the blocks on the mobile. I changed that by additional customization. Check now.
3) Provide us with FTP access. We’ll check the issue with the sticky columns on the desktop.
Regards