1. u can stay as long as in Qatar if ur id is valid. the moment u exit from any of these countries u have to renter within 6 months. that means every 6 months u have to keep on traveling too and fro

2. no restrictions by road

3. u can use ur car with Qatar no plate. till d validity of the visa. but u have to take permission from border. they will register ur vehicle at border. once u take Qatar vehicle u can drive with ur Qatar licence. but others are not supposed to.