It is not recommended nor best practice, since you will run into the problem with duplicated objects from two sources. If you split things up into e.g. managing certain commands or notification apply rules outside the Director, you can go that advanced route.
For starters, I would recommend to choose either one or the other direction. If you want to start learning and playing with the Director, I’d recommend to build a staging environment, or use a VM (Vagrant Box for example) to play around and test your later migration to the Director.
In terms of the initial changes - the Director kickstart wizard imports specific object types from the core’s REST API on the first start. This generates a couple of templates and other stuff making the work with Director a breeze.
One important thing to note - these imports mark these objects as external sources, and as such, they won’t be deployed. You can look into the Deployments tab and render the configuration which should be deployed, that gives you a good indication on what’s going to be changed in reality with a unified diff.
