It depends what kind of job: corporate; expect 3-4 interviews. Union: they have an extremely high turnover so you might get hired on the spot. Union jobs aren't always easy to do, I would ask the HR person to show you around before you say yes.
When does an employee at gate gourmet start to work after the New Employee Orientation?
It depends on the job; union related, I believe that would be your first day but if you're corporate than its one of your first days within two weeks.
Management is not understanding and the environment is very high stress, making at least 10% of employees irritable at all times.