We are considering either coding a new Shopify Theme for a one-off site from scratch, or customizing an existing theme. I know that in WordPress, it's taboo to edit theme code directly, because when a theme author releases an update, you then lose all of those changes. It's important to keep themes and plugins up to date for security reasons.
Is it the same in Shopify, or does the Liquid language bypass any security issues? Can we just edit the theme code, and be done with it? If not, what do developers normally do, in order to add in custom functionality, or change the look / flow of pages?
Also, in WordPress I normally use Atom, and have lots of shortcuts I can type to produce fast code snippets. I realize Shopify's editor is all online, so I can't use Atom. Does Shopify's editor have any snippets feature, as well as code tidier add-ons?