1. A horizontal carousel can be enabled via Theme Settings -> Single product -> Images -> Thumbnails.
2. As for the image space, sorry to say but right now there is no option in Theme Settings available to achieve that. It requires Customization and this is beyond our limitations and support policy scope.
3. Please navigate to Theme Settings -> Styles and colors and adjust the border-radius per your needs, if you want to adjust border-radius only for the single product, I suggest use our theme presets: https://xtemos.com/docs-topic/theme-settings-presets/