I am guessing you are offered as contract, not permanent staff. Only permanent staff gets the yearly bonus. But it's not much anyway, just 2 months. Yes, there is a ranking system in Exxon for permanent staff. And yes, you will be numbered from 1 to whatever number. But of course you wont know your number, every year they will only tell you if you are in the top 1/3, middle or bottom 1/3. I am not sure if there's any for contract.