Regarding the stereo, yes, you will need a suitable steering wheel control interface to make it work. Connects2 is the most popular brand for this, and you can buy them in Australia; they are distributed by Stinger Australia, and Stinger products are readily available at most store. Though you're very likely to need to order the particular part in. Otherwise, source from overseas, including ebay.
You'll need the CTSAR002 interface, and a 'patch lead' that connects the interface to the socket on the back of the Alpine, which is the CTALPINELEAD.
Connects 2,Car Audio integration specialists
There's no compelling reason to use Alpine speakers, except for brand loyalty. They are decent, but there are better speakers for the money, whichever ones you're looking at. If you're in Sydney, you can go and see a place like Fhrx Studios, who sell a massive range of quality gear. You might prefer brands like Focal, Boston Acoustics, Crescendo, Morel, DLS, etc. All highly regarded, and speaker-specialist brands. Ditto their subs.
Up to you about the subs and boot space. Whilst you can fit a sub in the parcel shelf for 'infinite baffle' application, you're more limited in the choice of what sub suits; but do-able. Easier to buy a conventional sub and have a suitable subbox built to the specs.
Those wheels might be ok. With the appropriate width and offset, you may not get that amount of scallop/dish though. Not sure; always hard to predict. For the best 'look', of course the car should be lowered too, but you may already have that covered.
If you have a 2.4JTDm with front Brembo calipers, be totally sure the wheels will fit and clear the calipers behind the spokes. It does limit your choice.