Are we talking about the same RAAF that just spent $2billion to buy 4 C-17s? Now they're going to get a few SQUADRONS of F-22s and F/A18E/Fs for $15billion? Not a chance. I've also seen in print recently that the F-22 is not for export. That may change but we won't be on the list of approved buyers if we pull out of JSF.
The current RAAF F 18s do not have all the gear for carrier ops. It is useful to have the ability to stage through a US carrier if nothing else. See the last big war for examples - Malta, Norway etc. It is in any case a relatively easy aircraft to fly on and off the deck.
Have many carrier landings in the F/A18? Any understanding of how the US Navy operates their carriers, other than from watching Discovery?