3 - don't forget the XLA.

Who completes the timesheets, the employee, or a central admin? If the former, you should create a separate workbook per employee and put in a central server directory, so the employee can update, then one of the XLA functions would be to consolidate them all. This process should also validate that the total jobs time equals the daily worked time.

BTW, the start date should be a function of the timesheet generator function, an inpout to that function.