Since some compilers (and lint) will warn about discarded return values, an explicit cast to (void) is a way of saying "Yes, I've decided to ignore the return value from this call.

This would be better

printf("Hit 'ENTER' to exit\n");
fflush(stdout);
(void)getchar();

In case char *name="Yankee Duddle"; string literal turns into an unnamed, static array of characters, and this unnamed array may be stored in read-only memory, and which therefore cannot necessarily...

I think if possible you should go as local as you can keeping in mind memory.

As far as processing power is concerned, you should'nt care unless you are working on a system having limited amount...

See srand (http://www.cppreference.com/stdother/srand.html) and rand (http://www.cppreference.com/stdother/rand.html)

I would recommend you to read this tutorial
http://www.cprogramming.com/tutorial/cfileio.html

We don't use this...we use
rewind(in);

Are you sure about what you are asking...if yes, please make it more clear