1. MySQL, MariaDB, PostgreSQL, Oracle, Microsoft SQL, and Aurora.
2. Read replicas are read-only asynchronous copies, while Multi-AZ has one read-write master and a synchronous slave replica that isn't accessible until failover.
3. Primary instance for writes and replica instance for reads.
4. Snapshots don't affect Aurora's availability.
5. Snapshots can't be restored to an existing cluster.
6. Implement a read replica and point the BI to the read replica.
7. Make the RDS subnet private and specify the EC2 security group as the source in the RDS security group instead of the subnet address.