I would like to copy and paste a "scene" or a group of "scenes" to use it further on the scene/cues line for instance for a loop. How is it possible ?
Select one or multiple scenes and press Cmd+C / Ctrl+C, then select an empty scene cell and press Cmd+V / Ctrl+V. You can also drag&drop with option key pressed to duplicate.
Is it possible to save a scene or a group of scenes to transfer it to another Madmapper project ?
You can but some parameters might not exist in the other project. For instance if you store parameters of "Quad 1" in a cue and paste it in another project where there is not Quad 1 surface, it will have no effect. You can enable Cue Inspector to understand what's in the cue, go to Preferences / Misc / Show Cue Inspector. And check the documentation available from menu Help