2. Not sure.
3. For most languages, the default is to use prettier for formatting. You can disable `format_on_save` globally, per-language and per project depending on your needs. If you ever need to save without triggering format ("workspace: save without formatting").
Prettier is /opinionated/ -- and its default is `singleQuote` = false which can be quite jarring if unexpected. Prettier will look for and respect various configuration files (.prettierrc, .editorconfig, via package.json, etc) so projects can set their own defaults (e.g. `singleQuote = true`). Zed can also be configured to further override prettier config zed settings, but I usually find that's more trouble than it's worth.
If you have another formatter you prefer (a language server or an external cli that will format files piped to stdin) you can easily have zed use those instead. Note, you can always manually reformat with `editor: format` and leave `format_on_save` off by default if that's more your code style.
- https://zed.dev/docs/configuring-zed#terminal-font-family
- https://zed.dev/docs/configuring-zed#format-on-save
- https://prettier.io/docs/configuration
