This is what state locking accomplishes, by preventing other users from modifying the state file while a Terraform operation is in progress. This prevents conflicts and data loss.

In Terraform, when you use the count meta-argument, you can reference individual instances using an index. The indexing starts at 0, so to reference the "name" value of the second instance, you would use aws_instance.web[1].name. This syntax allows you to access the properties of specific instances in a list generated by the count argument.
References:
Terraform documentation on count and accessing resource instances: Terraform Count

You do not need to use different Terraform commands depending on the cloud provider you use. Terraform commands are consistent across different providers, as they operate on the Terraform configuration files and state files, not on the provider APIs directly.

This is a secure way to protect sensitive data in the state file, as it will be encrypted at rest and in transit2. The other options are not recommended, as they could lead to data loss, errors, or security breaches.