Deploy BIG-IP ASM for API Application
The swagger file will contains all information related to the service, so you can just start checking the event logs for any violations matching with the application, and then tune the policy accodingly.
If you copied the policy, it will copy all its entities only if you have applied all changes on the old policy. But the learning suggestions will not be copied.
So you can go with the test enviornment first and create it in the learning mode, and when everythign is stable, you can import the same policy in the production enviornment, and start monitoring the policy.