Hi BillB,
The South Aussies have there own fishing chatsite, please refer to the attached website; http://www.fishsa.com/
You can join up, then ask a few questions to the members.
KG whiting are a year round proposition, but as with all fish some times are better than others.
When I lived in Adelaide - I caught good whiting in March / April.
Tackle: size 4 or 5 hook (for legal to 40cm fish), with 10lb / 12lb leader (if fishing for the bigger whiting; kilo plus, then 15lb would be better). Braid is an advantage as it detects the slightest of nibbles. Paternoster rig and sinker to suit conditions. About a 45 gram snapper sinker was suitable for fishing up to 25 feet.
Rod and reel: something that would handle a bream is all that you need. 7ft rod (soft tip), with a 2000 / 3000 class reel.
Berley: is a must. I would buy a gallon of cockles and half of that was crushed up to be used for berley. Throw some crushed cockles over board when you first anchor up, or with a berley cage release crushed cockles near the bottom. I always had another berley cage with squid, cockles and pellets in it as a berley that sat on the bottom - used more for slow release of berley. If no fish in say: 20 minutes move to a new spot.
I preferred frozen cockles to fresh and would always have the point of the hook sitting in the black part of the cockle. KG Whiting apparently like the black bit best.
Other baits - squid or razorfish.
Bottom: broken bottom is what you are looking for. That being weed and sand bottom, can be a large sand patch surrounded by weed or a more patchy bottom.
I found that in shallow water (under 20 feet) slightly mirky water was better than clear water. If clear probably better to fish a little deeper.
Always hold your rod, feeling for the slightest touch. I found it rare that these fish would hook themselves, so trying to juggle two rods is a waste of time. If losing hooks (not feeling bites) then most likely leatherjackets - time to move.
Hope that helps.
Cheers
Shane