I don't know how they do it in Vic, but here in NSW your ATAR is calculated off of your best 10 units, and 2 of those must come from English. Therefore, in order to receive an ATAR you must pass at least 1 English course.
And as far as I know you
only need to pass. However, since 2 of your units must come from English, you'd want to do well in your course if you're aiming for a high ATAR. Some universities may offer bonus points to students who excel in non-English areas and are disadvantaged by this. I think I've heard that the University of Newcastle does? I'm not 100% sure.
The courses they offer us are: English Life Skills, English Studies, ESL, English Standard and English Advanced (then there is Extension 1 and 2, but you do those on top of English Advanced.) You're eligible to get an ATAR if you pass Advanced or Standard (and with certain criteria ESL), but not any of the others.
As for study scores, I haven't even heard of them.
I hope this wasn't too convoluted or crazy. If you need me to clarify anything, ask away