Can I access to Portainer to create new containers?
Yes, you can but you need to request the access by CAU. This guide explains how to migrate containers to our physical docker machines, but the main goal is creating a unique Docker environment (this model includes new deployments too).
Is it strictly necessary to configure the Stack with the same parameters?
Yes, it is. The parameter values can be modified but not removed from the Stack. Moreover, you can add another definitions.