How to create Gantt view grouped by users
I'm new to Odoo Community 12. I'm starting to develop all the tools my company have now developed on other platforms (Excel, Project, Trello...) and something I've been requested to do is to create a Gantt View in which the root of each node will be an Employee and under it I need to have all the projects he is involved in, with the START and END date. In this way, my boss can check who is available for a certain date.
For my starts, I've been editing the project module using the web tools, I have not code everything for now, so I think I will have to migrate all the changes I've done to a file, and trying to don't lose anything.
Can I extend the default Project class to modify it? Or I need to create a new module? I want it to be the default project.project so I can use it in all other parts of the system, not just a new module.
Can I REPLACE the default Project View? So finally I can have the same XML I have edited using the Edit Form view?
How do I create a new Gantt View for Projects as described above?