The first thing you must consider when renting a car, are the rates of the company. It is often cheaper when the rental period is longer. We must also take into account that renting during the weekends usually has a higher price.
The fuel is always going to be part of what the rental. As a general rule you are suppose to surrender the car with a full tank and you must return it the same way. If not, two things can happen: they charge you of what is missing to complete the deposit or charge you before you pick up the car with a full fuel tank and return if you meet the conditions.
The type of insurance you have with the rental car is a third party insurance, ie only cover the damage caused to another vehicle, but not yours. You have the option of getting a full insurance and is the most advisable course. If anything happens to you while the car is parked, all you need to od is call the insurance company.
One thing to keep in mind and that is usually very easy to forget is to ask about the miles allowed. They usually include 350 km per day, although companies can reduce these cheaper kilometers. In the event that this limit exceeded, they will charge the extra miles.
Companies are constantly changing their rates to match demand, so the price varies depending on demand and how early you book the car. As you know the exact dates of your stay we recommend that you rent it as soon as possible and not wait any longer.