Hello,
1. Check if you have this issue with our theme only or with default WooCommerce theme too. To do this go to Appearance > Themes > install and activate Storefront theme (Official WooCommerce theme) and try to proceed to checkout and do the test purchase. We’ll be able to help you only in case problem persists with our theme only. If you have the same issue even with default WooCommerce theme then you need to contact their support to fix the issue.
2. We use default WooCommerce functions for this – update cart button. You may try to look for additional plugin that may help you to implement this.
3. This is default WooCommerce option and they use paragraph by default, it’s not a link. There is no any option in our theme to add link for this instead of paragraph.
Regards
