Yes, you can put Doona in a car without the base. It is just important to make sure that the car has a space for the Doona and that the base is not too close to the car.
Yes, you can use Doona without Isofix. However, please be aware that Isofix can help to improve the performance of Doona.
Yes, you can use Doona without head support. However, it is important to make sure that you are using a product that has been specifically designed for use with Doona.