Alright,firstly when applying for jobs like McDonald's don't list your academic award for music in year 9(unless maybe applying for a retail music store..and even then) that stuff is irrelevant, Business Week is ok,if you can talk about something you've learnt. The most important is putting any prior work experience so definitely put in your Myer exp. Don't think too much on qualifications and more towards extra-curricular,did you do any sports at school or join the SRC club? List those things,that shows you have time management and can handle some stress,learning teamwork etc... Anything you put on your resume-correlate it to skills you've learnt or experiences(that are relevant ) - important when they ask questions such as "tell me about a time..when you were stressed and how you dealt with it" etc..
Most retailers,fast food, any major corporate basically does their entry recruitment online these days.You can still try and hand it in manually but more often then not they will just tell you to apply online.
One thing you should know to calm your worry is that you DON"T NEED ANY QUALIFICATION to get a job at McDonald's or similar.JB HI FI tends to hire people with mostly some sort of previous retail/sales experience I've heard and Gloria Jeans might be a job where having a barrister qualification can really help you land the job,but for majority you don't need anything.
If you don't mind working at McDonald's then I suggest you start there,it's probably the easiest of the three you've mentioned to get a job at, and working for a few months with all the training they provide will really help in lending those as I like to call "1st tier" retail jobs like Myer,JB HI FI,etc..(or any other minimum wage job really),because they tend to hire people with prev. exp, and with all the uni applicants they can be choosy.
Also to mention,if you want to work with Coffee(your name ..suggests an interest I'm guessing),after initial probation period (where you are still learning and they pay you low low) you can start getting involved in McCafe and basically work there all day as a shift, McDonald's also offers good training for the Cafe.
All in all, apply for everything you can online,hopefully you'll have a few interviews and you can learn from there.Although really all some jobs want is good availability and someone who can be taught and can communicate(as easy as this sounds,it can be harder to convey in interview conditions).
