The most common opening hours for car hire companies at this airport are:
Monday: 08:00-17:30
Tuesday: 08:00-17:30
Wednesday: 08:00-17:30
Thursday: 08:00-17:30
Friday: 08:00-17:30
You'll find more details about the exact times during the booking process.
If upon arrival at Melbourne - essendon you wish to purchase additional services or must pay any outstanding charges, you must do so in the currency of Australia, which is AUD.