there is no ultimate stack that would fit all your needs. You will use something else based on what you are working on and for whom you are working. No matter what tech you choose, you should aim for simplicity and ease of maintenance.
Picking up a perfect CMS isn't an easy task. You have to consider many things before picking the one and only. Here is a small guide explaining the different aspects of every CMS.
Is implementing a full-fledged CI/CD in your project difficult? It depends.
The most difficult part is making the first step because sometimes it requires changing the habits of the whole team. In this article, I'll explain how to do it step by step.