For the Error Messages, reset the workspace layout:
go to Window -> Workspace Layout -> Reset '<Your layout name>'
Then delete the Dreamweaver Cache file from the users configuration folder:
The message about uploading the database connection will occur if your site definition is defined to use the remote server as the testing server. I recommend using a local testing server instead.
The option to choose a template was removed from the Data Assist create pages wizard, you will need to apply the template after the pages are created, or use Framework builder Themes and Plugins.