Queue names are limited to 80 characters. Alphanumeric characters plus hyphens (-) and underscores (_) are allowed. Queue names must be unique within an AWS account.
After you delete a queue, you can reuse the queue name.
https://aws.amazon.com/sqs/faqs/

When a user is configuring ELB and registering the EC2 instances with it, ELB will create a source
security group. If the user wants to allow traffic only from ELB, he should remove all the rules set for the
other requests and open the port only for the ELB source security group.
Reference:
http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/using-elb-security-groups.html

Amazon Relational Database Service (Amazon RDS) is a web service that makes it easier to set up, operate, and scale a relational database in the cloud. AWS RDS supports popular DBs, such as MySQL, PostgreSQL, MS SQL and Oracle. This means that the code, applications, and tools user is already using with existing databases can be used with Amazon RDS too. In short, it is a managed Relation Database offering from AWS which manages backups, software patching, automatic failure detection, and recovery of Database.
Reference: http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Welcome.html