Dennis,
I was wondering if you have any previous experience implementing SSO authentication with Salesforce before and if you had any pointers. This morning I created a developer account on Salesforce and enabled it as an identity provider and am in the process of trying to get Drupal to act as the service provider. The Salesforce documentation seems to be somewhat outdated in parts.
I also think it would be a good idea to have walk through of how the users are setup in your Salesforce Community to understand how their profiles and privileges would map over to Drupal. I'm not convinced that all the necessary data would be passed through the SSO process so we may have to implement a secondary step of pulling user data via the Salesforce API to validate the users' access level.
Let me know when would be a good time to review the Salesforce Community setup and if you think you may have any helpful info on getting the SSO implementation completed.
Thanks,
Ben