For this, we would suggest you walk into the nearest service center as they will be better people to assist you with the service cost. You can click on the following link to see the details of the nearest service centre and selecting your city accordingly - Service centre.
The XC90 is available with four, five, six or seven seats, depending on trim. Whichever version you choose, each seat is designed so that everyone sits in luxury.
For the availability, we would suggest you walk into the nearest dealership as they will be the better people to assist you because it depends on their stock book. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Car Showrooms
The Volvo XC90 mileage is 17.2 to 42.0 kmpl. The Automatic Diesel variant has a mileage of 17.2 kmpl. The Automatic Petrol variant has a mileage of 42.0 kmpl. Moreover, the actual mileage depends on several conditions driving style and condition, road condition, service interval, etc.