I use "hello" so much as a native speaker! At school when I see people, I always greet them first: "hiya", "hey", "how're you?", etc.

"G'day", where I'm from actually. :) If you mean saying hello to the same person several times a day (eg. your workmate), then that's a little weird.

I must say I've never been greeted with your suggestion "hi, shitface" (which is a swear word and would be offensive unless you were joking on with a friend...). If I go into a shop I'll often say "hello!" cheerily to the shopkeeper, and if I see someone on the street who I know I'll often say "hi!", "you alright?" or just "alright?".

Hey Gannicus! Spartacus is here always waiting for you.