C :: Dereferencing Of Void Pointer

I could understand void pointers I created the following program:

Code:
#include <stdio.h>
#include <string.h>
int main(void) {

char word[] = "Zero";
int number = 0;
void *ptr = NULL;

[Code] .....

The program works fine, however i really want to fully understand what is going on with the dereferencing of the void pointer, for example: With the following code:

Code:
ptr = &number;
*((int *)ptr) = 1;

Why can't you just do:

Code:
ptr = &number;
*(int *)ptr = 1;

And again with this code, (i'm guessing it's becuase its a pointer to a pointer?):

Code:
ptr = &word;
strcpy(ptr,"One");