1) Apart from the aforementioned reasons (which are the main reasons), there is another reason for the matinal hand-washing. This is because of an evil spirit which rests on the hands in the morning, which goes away when the hands are washed. (Shulchan Aruch and Mishne Berura 4)
2) Ideally one should wash one’s hands in such a manner that the water reaches the entire palm of the hand, until the wrist. In the event that he is unable to do this, one can wash until the end of the knuckles. (Mishne Berura ibid)
