1. Is this an internal form or a public form? For an internal form, the user can go to their completed tasks list, find the submitted form, select it and view the action history. That will show where the form is in its process. For public forms, the user will not have direct access to the action history. You can configure emails to be sent to a provided email to update them after each step.
2. Comments are only available in the action history and the monitor page to record why a specific decision was made. If you want to include comments in an email, you should create a comments field on the form and use that.