Automatically export Worktitems

well sort of yes,

if u create a query to identify the workitems, display that query result in the wed UI,
select the printable form button  or the export to csv and then get the URL from the browser.. then u can use curl or somesuch from the commandline to invoke that url again...

You should investigate the reportable REST API: https://jazz.net/wiki/bin/view/Main/ReportsRESTAPI
This is what is used to populate the data warehouse via RRDI or Insight.  A REST call such as this:
https://<host:port>/ccm/rpt/repository/workitem?fields=workitem/workItem[id=123]/(id|summary|itemHistory/comments/content)
will return the id and summary of the workitem, as well as all comment contents from each version of the workitem for workitem 123.  The API is quite powerful and you can customize the sample REST call above to return more attributes from more workitems and include search predicates (including based on modified date) so that you are not retrieving the full contents of your repository every time you run it.