the first error is happening because the page that the wizard is trying to create is already opened in dreamweaver.
It sounds like you are running the Wizard multiple times and creating the same pages each time.
If the pages that the wizard is trying to create already exist in your site, it will cause the issues you are experiencing. either delete the pages that have already been created before running the wizard, o on the Manage Pages tab, change the names of the pages that will be created, so it will create unique pages.
on the manage pages tab, you may need to edit the properties of each page to customize the columns that will be used.
