Ma sha Allah
you have got good cars..
as far as cruise control in civic is concerned,
just acheive speed and press cruise control button on stearing, the car will start cruising, as soon as you will press a slight brake, cuise control will be deactivated. you can increase or decrease cruise speed with up down button on stearing, or even by pressing accel bit more (for curise control speed should be above 40kmph i think)
dont know about prius
may be same procedure..