PDF Form scripts

I need some Javascript completed on a PDF form we have created. In particular : 1) Field : total_leave_days must be a calculation based on date field: start_leave_date and end_leave_date (sum of days based on dates) 2) Field : Todays_Date must be the current date automatically populated 3) When employee digitally signs document (field: employee_signature) the field employee_sign_date should be populated with the current data and all fields except manager_approcal, manager_signed_date and manager comments should be made read only 4) When manager_signature field is populated, all fields should be made read only & manager_signed_date should be populated with current date 5) After manager_signature, form should be emailed to an email address