Is it advisable to extend the files(Specifically Live Order), and create the extensions, and then make them available for customers? I don't think it's recommended, but I wanted to confirm.

I'm not entirely sure what you're suggesting, but generally: • If the extension you're creating is aimed at SuiteCommerce sites (rather than SCA ones) we don't recommend extending any core modules because of the possibility of them breaking when we perform automatic updates. • If the extension is for SCA sites, then it's fine but your customers should be aware of what you've done so that when they upgrade their SCA version, they know to diff the modules you've extended to make sure there are no breaking changes.

Thank You..