2) yes, https://docs.windmill.dev/docs/advanced/local_development
1) since you can run them locally, you can also run tests as part of your CI. You can also deploy a full windmill as part of your CI, deploy to that local instance, run some e2e tests by calling the webhooks, and then only deploy once those work.
Note that we have a full drafting system baked in into the webeditor as well: https://docs.windmill.dev/docs/core_concepts/draft_and_deplo... and have support for folders with different permissions and you can create workspaces so you may implement dev/staging/prod in any fashion you like (different folder, workspace, instances)