add to that Perth is the only airport in the world I've flown into that actually goes out of its way to make a runway with tailwind the duty runway, and you would have 21 as the most used runway I would think
I'm not a tower controller but my understanding is its the criteria are the same at all Australian controlled airports, possibly except SY. Runways are ordered in terms of noise abatement preference. If the the RWY is dry and the downwind 5 knots or less (or maybe less than 5 knots?) on the preferred runway has to be used. For PH in descending order its 21 and/or 24, then 03 then 06.
Re PEA airspace, F150 over the aerodrome does seem a little greedy. However the only proposed movement with regard to their airspace I've heard in years was they wanted
more (higher around Bindoon).