Answer 1

when you need more than one object of a class, you can't do it with everything static
imagine you have a class circle and want an array of 100 circles, each with different coordinates

class Circle{
int x, y, r;
}

circles=new Circle[100];
for(int i=0;i<100;i++)
circles[i]=new Circle(rnd.nextInt(),rnd.nextInt(),rnd.nextInt());

if x, y, r were static, all circles would have the coordinates of the last one