Literally just got back from the shop and was really lucky as there was a longboard expert in today. The shop is dripping wet (Manly or Bondi) and the chap was called John, and is normally in the Bondi shop. He was amazing, which is why I wanted to post back here immediately before I forget what he was saying! He is a regular competition long boarder yet loved the fact that I was relatively new to it all and just kept showing me loads of things and getting excited!
In terms of fins, he said that in and around Sydney a single fin setup is good, in that the waves aren't massive generally (beach break), He said if you go somewhere that the waves are more critical and bigger, a tri fin setup can give you that little bit xtra bite when taking off and turning etc which can make all the difference. I opted for a Dion dog cutaway 8" from his recommendation as a good all rounder. They had everything you could possibly imagine, and even really expensive ones in the same style, but he said this one was just fine – nice when someone doesn't sell you the most expensive thing unnecessarily.
So onto the board advice:
He showed me a great Robert August, 9'4'' 22 3/4 2 3/4, double concave at back, squarish tail, concave at front too, and talked me through all the subtleties and what they do. In terms of my size he said that 9'2'' was perfect, and no more than 9'4'' because you don't need it. After me describing my board whilst he didn't know the make he said the dimensions were perfect and that I should ride it until its knackered, or a couple of years at least. He also mentioned never going to thin with a long board because you loose too much kinetic energy when paddling because of the flex.
So there you have it, no need for a new one right now which is good news, and good to know I've found a shop on the level, telling me not to by a new board, and they have such great longboarding supplies.
Just need to learn footwork now, I think that, rather than board, will change my surfing experience more than anything! (any tips would be appreciated)