Hi there...
Whilst all the points you listed are relevant to any proposal, they mainly cover the areas that you are most concerned about....Put yourself in managements position..... you need to ensure you cover off not only those points already listed but how the job will actually operate while you job share e.g. handover (how this will be done), benefits to the employer, demonstrating the 'win win' situation for all. From a management point of view they will likely want to be convinced that job sharing has a very low impact on the business and will want to be convinced that you can work it out between you both...Good luck!