A folder in Constant Contact remains a folder, you can find more information about our functionality in the API with your Library here. A Campaign references your newsletter as a whole, which would be your bulk email. The list number or ID rather would be an object of a Contact list. Your start date i assume is your scheduling for when you would the email to be sent. Status would reflect if it is draft (still editable), scheduled or sent. The listype would be if it were a System list or a Contact list. A system list would be Removed, Active and Do-Not-Mail.