This name will be part of the url of objects stored in the bucket, e.g. https://s3-eu-west-1.amazonaws.com/mybucketname/myfile.jpg
Public read access
You can set this to not public and still mark objects in the bucket as publicly readable as they are stored.
Just the main AWS account holder / you is fine.
Creating a user key pair to programmatically access the bucket
AWS Management Console > Security, Identity & Compliance > IAM
Access type: Programmatic access
Select “Attach existing policies directly”
Policies: Select “AmazonS3FullAccess”
This key pair can new be used to access all of the S3 buckets.