The AMNRL are calling their 2 halfbacks, 'halfback' and 'flyhalf'. What positions are they referring to and why are they using the union position?

Fly half is pretty much stand off.
Half back usually means scrum half, but can mean 6 or 7.

I'm all for America rephrasing the sport if it helps them adapt to it.

lets not forget, 'five eight' is also used in league down under but you never hear it used over here. its not an issue.

Why has the term "three-quarter" stuck here but "five eight" hasn't? -.-

dont ask me. i cant speak for those deviants down in the colonies

And why are there no one-quarters or 3/8ths or 1/8ths or even zeroes (though we could all name a few of those) ?

That would be Rob Burrow.

i did wonder how long it would take someone.

Lee Smith

Wouldn't Mr Hock be the man to ask about an 1/8th ?

Three-quarters has stuck because that's always been part of English rugby descriptions, as has half-back and full-back.

The name was 'five-eighths' is an Australianism.

Five-eighth (5/icon_cool.gif was used because at the scrum the stand-off is between the scrum half (1/2 = 4/icon_cool.gif and the three-quarters (3/4 = 5/icon_cool.gif.

Full Back = 8/8 (1)
Wingers/Centres = 6/8 (3/4)
Stand-Off = 5/8
Scrum-Half = 4/8 (1/2)

The 7/8ths you'd think would probably be the wingers (who are usually deeper than the centres).

The rest of the positions are for the forwards, so, looking at the scrum, you'd think it would be something like:
3/8 = Loose Forward
2/8 (1/4) = Hooker
1/8 = Second Row
0 (0/icon_cool.gif = Prop

I dunno. That's what I reckon anyway! Bloody maths and RL shouldn't mix!