MAILING SQL SERVER
Below a post aimed to alert you if a volume is exceeded on your SQL Server, for example, the basic transaction data may exceed certain thresholds for that access your agent SQL SERVER, configure it in such a way as to send mails.
Audit SQL SERVER
You gave rights to a user, you want to know if that user has rights has spread another user, simple to make, use SQL SERVER Audit, create an audit specification
You use both nodes Audit (audit and Create output formatting) & Specification (Create the specification)
Link : https://technet.microsoft.com/en-us/library/cc280500(v=sql.105).aspx
For your security management of your database, choose the concept of Role personalized, permission on a schema, add users to your role (Just as it would have been done with the Principal, Identity, Permission, Claims in C # ). Associating the scheme now to the role and not to different users.