For each step you can define which fields should be included in this step. "Fields" includes core-fields like "Title", "Body" or "Authoring information" as well as fields defined by other modules (e.g. Date).
This module allows users with the appropriate permissions to edit the allowed values of a CCK field from the node create/edit form itself. This is much more convenient for the site developers, and as it has its own permissions you can also open it up to the client*. There are two permissions: users with Edit CCK allowed values will be able to edit the allowed values of fields which have been explicitly configured to allow it; users with Edit any CCK allowed values can edit the allowed values of any appropriate field.
If you're using the Edit CCK allowed values permission then you need to explicitly configure the fields you'd like to be edited by users in that role. If you go to the field edit screen you should see a new checkbox titled Edit allowed values. Check that and save, and the link should appear on the node form for users with the right permission. This setting is configured per content type and not per field.