I wanted to know if it is okay for us to do the masaah (wiping of the head) twice so that we are confident that water has reached the roots of the hair ( incase of long hair). Similarly, can we do the masaah of the feet ( wiping of the feet) twice to ensure that it is done properly ?

No. Repeating the wiping is not okay, and you do not need to reach the water to the roots.
In case of long hair, all you need to do is disperse the hair from the middle of the head, and scan the difference place.