I have written to my potential PhD supervisor and he has replied that he would be happy to supervise me on a project. I have not applied to the university yet and I think the process will take several months. During this process I would like to take some time and use it to develop skills and my résumé before getting into grad school (I call this "pre-doctoral fellow").
Professor X has with the "Équipe" Y all that is ideally situated for my needs.
What would be the academic position that I should apply for some months in Y with professor X to develop important skills for the success of my future phd program? A pre-doctoral fellow? How much time is the minimum/maximum I can apply for? In general, how would be the letter to professor X soliciting it go? Does this project is founding? Advice and comments are really welcome!