1. How does a computer which can only make real calculations possibly generate a genuinely random number?
In reality, a computer cannot create a number that is truly random, but the Random class uses a seed that produces a number that would stand up as genuinely random under close statistical scrutiny. To find out more about seeds and generating random numbers, take a look at the article at https://en.wikipedia.org/wiki/Random_number_generation.
2. Where is the code that manages the creation, showing, hiding, and scrolling of list items and ListView?
It is tucked away in the BaseAdapter class and we don't need to know how it works. But if you are curious, you could find out more about it at http://developer.android.com/reference/android/widget/BaseAdapter.html.