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Introduction:

1)

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ssm:UpdateInstanceInformation",
                "ssmmessages:CreateControlChannel",
                "ssmmessages:CreateDataChannel",
                "ssmmessages:OpenControlChannel",
                "ssmmessages:OpenDataChannel"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:GetEncryptionConfiguration"
            ],
            "Resource": "*"
        }
    ]
}

2)

3)

https://it-infrastructure.solutions/spinning-up-your-first-ec2-instance-aws/

4)

Sources:

AWS Systems Manager – Preise – Amazon Web Services (AWS)
Für AWS Systems Manager fallen keine zusätzlichen Gebühren an. Ihnen werden nur AWS-Ressourcen berechnet, die durch AWS Systems Manager erstellt oder aggregiert werden.
Setting up Session Manager - AWS Systems Manager
Set up Session Manager to connect to the Amazon EC2 instances in your account.
Create a custom IAM instance profile for Session Manager - AWS Systems Manager
Create a custom IAM instance profile that provides permissions for only Session Manager actions on your instances.
IAM roles for Amazon EC2 - Amazon Elastic Compute Cloud
Allow applications to make secure API requests by creating IAM roles and assigning them to your EC2 instances.