Honda CR-V mileage of the MT version would be giving 10.9 kmpl on the city roads and 13.7 kmpl on the highway conditions. Honda CR-V mileage of the AT version would be giving 10.9 kmpl on the city roads and 12.0 kmpl on the highway conditions. To know more details of the car, please do follow the site: http://www.cardekho.com/carmodels/Honda/Honda_CR-V#Honda_CR_V_Mileage
It may be possible through outside car modifiers. However, since the car has been designed as a 5 seater, adding the rear seats will be tricky. They are unlikely to be comfortable and will leave you with negligible boot space.
You can find the engine no stamped on the engine itself, but if you are unable to locate it, you can also search it on the product information tags on the car, which generally found under the hood near engine bay and on the door frame.