Question: Is it possible for report services to use an existing database that's already been created according to our organization's standards?
Answer: Report services cannot use an existing database, the Configuration Wizard creates a new database.
Question: Does report services create just one database?
Answer: Yes. If you reconfigure report services, the Configuration Wizard creates a new database.
Question: Does the report services installation make any other modifications to database objects other than in the database it creates?