Hi,
1. That's not a bug of HikaShop. That's a bug of another extension that you installed to compress/optimize your javascript files and which doesn't handle properly the HikaShop javascript files. Please contact the developer of that extension for help, or deactivate that extension and potentially use another javascript files optimizing extension.
2. The black background color comes from your template. I would recommend to contact your template provider for help on customizing the display of the template.