HELM 3: Helm test is not working? Getting "TEST SUITE: None"
Make sure your test configuration files reside under <chart-name>/templates/tests/ folder.
Regarding 2 and 3 - Yes, it creates a new pod, using the template you provided. The pod will run to completion, and if the Exit Code will be 0, the test is considered successful.
You can only test what was templated at the last install time. If you are writing a new test you need to upgrade the chart, or uninstall and re-install, to run it.