you may copy, store and burn iTunes Plus Products as reasonably necessary for personal, noncommercial use.
pretty sure this means that if we buy music from the itunes plus store we are aloud to use it for such things as in store background music and djing type things.
No. Using tracks for store background and DJ gigs is most definitely
not personal use by any measure whatsoever. "Personal use" means just that; your own personal listening. You are not licensed to use tracks from the iTunes Store (or any download store I am aware of) in any sort of public setting.
In the US, even having a performance license from the various rights licensing organizations - necessary for any public performance of any work to which you don't own the copyright or haven't been given explicit rights to public use, regardless of the source of the music - doesn't override that contractual arrangement. I don't know whether that applies in Australia or not.
So I would say that, in absence of a definitive, written statement from Apple or the APRA, you should assume that you
cannot use any tracks purchased from the iTunes Store in your DJ gigs.