Explanation
A bucket policy is a resource-based policy that defines who can access a specific S3 bucket and what actions they can perform on it. By removing unauthenticated access from the bucket policy, you can prevent anyone without valid credentials from accessing the bucket. A service role is an IAM role that allows an AWS service, such as CodeBuild, to perform actions on your behalf. By modifying the service role for the CodeBuild project to include Amazon S3 access, you can grant the project permission to read and write objects in the S3 bucket.
The AWS CLI is a command-line tool that allows you to interact with AWS services, such as S3, using commands in your terminal. By using the AWS CLI to download the database population script, you can leverage the service role credentials and encryption to secure the data transfer.
For more information, you can refer to these web pages:
[Using bucket policies and user policies - Amazon Simple Storage Service]
[Create a service role for CodeBuild - AWS CodeBuild]
[AWS Command Line Interface]

Explanation
https://docs.aws.amazon.com/vpc/latest/userguide/managed-prefix-lists.html A managed prefix list is a set of one or more CIDR blocks. You can use prefix lists to make it easier to configure and maintain your security groups and route tables. https://docs.aws.amazon.com/vpc/latest/userguide/sharing-managed-prefix-lists.html With AWS Resource Access Manager (AWS RAM), the owner of a prefix list can share a prefix list with the following: Specific AWS accounts inside or outside of its organization in AWS Organizations An organizational unit inside its organization in AWS Organizations An entire organization in AWS Organizations

Explanation
because of "as few maintenance tasks as possible on the underlying infrastructure". Fargate does that better than "one centralized application server"

Explanation
Use routing configuration on an alias to send a portion of traffic to a second function version. For example, you can reduce the risk of deploying a new version by configuring the alias to send most of the traffic to the existing version, and only a small percentage of traffic to the new version.
https://docs.aws.amazon.com/lambda/latest/dg/configuration-aliases.html The following are the steps involved in the deploy stage configuration that will meet the requirements:
Use AWS CodeBuild to add sample event payloads for testing to the Lambda functions.
Publish a new version of the functions, and include Amazon CloudWatch alarms.
Update the production alias to point to the new version.
Configure rollbacks to occur when an alarm is in the ALARM state.
This configuration will help to reduce the customer impact of an unsuccessful deployment by deploying the new version of the functions to a staging environment first. This will allow the DevOps engineer to test the new version of the functions before deploying it to production.
The configuration will also help to monitor for issues by including Amazon CloudWatch alarms. These alarms will alert the DevOps engineer if there are any problems with the new version of the functions.