is it possible to overload a final method

Yes, overloading a final method is perfectly legitimate.

For example:

public final void doStuff(int x) { ... }
public final void doStuff(double x) { ... }

Yes, but be aware that dynamic dispatch might not do what you are expecting! Quick example:

class Base {
    public final void doSomething(Object o) {
        System.out.println("Object");
    }
}

class Derived extends Base {
    public void doSomething(Integer i) {
        System.out.println("Int");
    }
}

public static void main(String[] args) {
    Base b = new Base();
    Base d = new Derived();
    b.doSomething(new Integer(0));
    d.doSomething(new Integer(0));
}

This will print:

Object
Object

Yes, very much possible.

A small program to demonstrate it:

class A{
    final void foo(){ System.out.println("foo ver 1 from class A"); }
    final void foo(int a){ System.out.println("foo ver 2 from class A"); }
    }


class B extends  A{
    final void foo(long l){ System.out.println("foo ver 3 from class B"); }
    // final void foo(){ System.out.println("foo ver 1 from class A"); } NOT ALLOWED
}

public class Test {    
    public static void main(String [] args){
        B obj = new B();

        obj.foo();
        obj.foo(1);
        obj.foo(1L);
    }   
}

Output:

foo ver 1 from class A
foo ver 2 from class A
foo ver 3 from class B