Signals Notebook: Is it possible to have different default experiment templates for different users within Signals Notebook and can a template selection be pre-filled

Yes, this is possible. Experiment templates can be created and assigned to different users or groups in SNB. If only one template is assigned to a user, that will be the only template they can select.

The first time creating a new experiment the user must select that template from the dropdown list. Once the template is selected that first time, it will always be auto-populated moving forward for adding an experiment, making it the default.