Two dimensions, two asterisks. Remember, an array is a pointer, and a pointer is an array (as you indicated already). A 2D array is an array of arrays, or an array of pointers, or a pointer to a pointer.

INT_CalculateIndex is a dangerous function, because that's not how multidimensional arrays work. When you do Array[x], the compiler converts it to *(Array + x). When you do Array[x][y], the compiler converts it to *(*(Array + x) + y). You cannot reach your target with only one index.