Just to get the permissions and roles, I believe there are no tools available.
>> But what you can get the the required data using a PowerCLI script. Please post the query in PowerCLI community, to share the script if someone has or LucD will help you out to do that.
With regard to security documents, refer
All about vSphere Security : vSphere Documentation Center
Best practices permissions [vSphere 4.0] : VMware vSphere 4 - ESX and vCenter Server
Authentication and User Management : vSphere Documentation Center
~dGeorgey