This is the type of block that is used to construct a collection of nested configuration blocks, by using a for_each argument to iterate over a collection value and generate a nested block for each element. For example, you can use a dynamic block to create multiple ingress rules for a security group resource.

Terraform can manage resource dependencies implicitly or explicitly. Implicit dependencies are created when a resource references another resource or data source in its arguments. Terraform can infer the dependency from the reference and create or destroy the resources in the correct order. Explicit dependencies are created when you use the depends_on argument to specify that a resource depends on another resource or module. This is useful when Terraform cannot infer the dependency from the configuration or when you need to create a dependency for some reason outside of Terraform's scope.
Reference = : Create resource dependencies : Terraform Resource Dependencies Explained

Terraform providers are not part of the Terraform core binary. Providers are distributed separately from Terraform itself and have their own release cadence and version numbers. Providers are plugins that Terraform uses to interact with various APIs, such as cloud providers, SaaS providers, and other services. You can find and install providers from the Terraform Registry, which hosts providers for most major infrastructure platforms. You can also load providers from a local mirror or cache, or develop your own custom providers. To use a provider in your Terraform configuration, you need to declare it in the provider requirements block and optionally configure its settings in the provider block. Reference = :
Providers - Configuration Language | Terraform : Terraform Registry - Providers Overview | Terraform

To import existing resources into Terraform, you need to do two things1:
Write a resource configuration block for each resource, matching the type and name used in your state file.
Run terraform import for each resource, specifying its address and ID. There is no such command as terraform Import-gcp, and provisioning new VMs with the same names will not import them into Terraform.

This is the workflow for deploying new infrastructure with Terraform, as it will create a plan and apply it to the target environment. The other options are either incorrect or incomplete.