does workbench access actual data in the salesforce org ? does workbench access only metadata. specifically does the workbench store the org data in its servers?
No, the data is not stored by workbench. If you're curious, you can read the source code. Salesforce.com takes your data seriously, and would not violate customers' trust in this manner. You can also host your own copy of workbench, since the source code is available for reuse and modification.