After logging into the projects account, click the Setting link displayed just to the left of the sign-out option. In the drop-down list, select the Portal Settings option to see the various settings option.
Now, click the Company Profile link and the Data Backup option that's available on the right side of the page. Once the Data Backup section is loaded, click the Export Data Backup button to trigger the backup process.
Once the backup process is completed, you will receive an email with the link to download the project information to your PC.

Couple of points to note:
Yes. Task Template option is available in Zoho Projects. To access task templates :

Learn more about task templates at http://www.zoho.com/projects/help/task-template.html
It is not possible to save the comments in a template because the Task Template does not support ownership, duration, notes/comments and documents/forums association.
The task templates can be deleted by the Portal Owner, Administrators and Managers.

The task templates can be deleted by the Portal Owner, Administrators and Managers.
Note: The options supported for Remind Me field are Daily / Weekly / Monthly

The Data Backup option, available in the Settings » Company Profile section, allows the portal owner to export all the project information - except physical copy of the documents - in XML format.
Note: This option is available only in paid plans.
To have the files downloaded, please send a request to support@zohoprojects.com
Yes. The Organize Tabs option, available in the Project Dashboard ยป Project Settings section, allows the Portal Owner and Administrators to turn-off the unused tabs for the project users and the client users too.
Currently, it is not posible to define or add a vacation or holiday in the project calendar.
Yes. After going to the Wiki module, click More option displayed under the Recently Attached Files section. Click the file names to download them to your PC.
