Hey Wazza,
We teach at Pinnaroo Point and it is a fairly easy beach for learners, nice and safe, but choppy water and you can't touch bottom. You need to be able to relaunch effectively in the Ocean as your toes may get nibbled off on the long drag behind an unlaunched kite all the way to Mullaloo or even Ocean Reef in a Southerly!
At 60kg a 148 is big, really big. Great for riding underpowered as a beginner but 15 knots will be about your max on your 12. You will definately need a smaller kite. An eight or nine would compliment your 12 and see you into the 25 knot range with a bit of experience.
Pinnaroo is North of Hillarys off Whitfords Avenue and is best ridden on a weekday as the weekends are becoming a three ring circus and will be VERY crowded this summer, especially Saturdays when the Whitfords Cat club are racing.
Come and see us at the beach for some pointers and a heads up on conditions and what to look out for.
Cheers,

AKS