Get in touch with the NSWKBA, a couple of committee members live up there and kite just opposite in the surf so they can give you some advise....from what I recall it's nasty and dirty and unadvisable.

Depends on which offshore direction. Best places are:
- NW the enterance
- ssw-sw longreef

everything else is not offshore and you could go to the northern beaches

I have kited the lake and heard of a number of other who have.
As JB says, its crap, soo gusty, you will get 15 to 20 knots for 5 minutes, then 3 knots for 5 minutes. Forget the lake unless you want to destroy your kite.

Re longreef, South with a hint of east is good, if its direct south or has west in it then it comes over the cliffs and is very gusty. Best to head south or north if you want to kite in westerly s (dolls kurnell boat harbor SW)

Or look at the google map I made for where to kite for the NSWKBA.com.au, or look at the NSWKBA.com.au website which I also made and had hundreds of hours of content put in by Gav, Selena and other members of NSWKBA New South Wales Kite Boarding Association.

Google map (click on a green spot for more info)
http://nswkba.com.au/index.php?option=com_wrapper&Itemid=75

Kite Spots:
nswkba.com.au/index.php?option=com_content&task=view&id=53&Itemid=103