Alex,
For flat water intermediate sailing, very hard to beat Kyeemagh on Botany Bay for summer NE seabreeze action.
I think you're gonna need a car anyway, so no need to live right on the beach. It's too expensive anyway.
You need to go to work everyday, but only sail once or twice a week, so you might be better off living close to a train station for convenient travel to the city, and then driving to the Bay on weekends to sail.
Check out the Illawarra line (blue one on this map-
transportnsw.info/). You could pick anywhere from Wolli Creek to Oatley and have between 15 to 30 minutes train to city, and 10 to 20 minute drive to Botany Bay. An alternative is to live closer to Cronulla beach for surfing. Still only 15 to 20 minutes drive to Kyeemagh to sail, but the train trip to the city will then be around 50 minutes.
Two bedroom unit will be maybe around $400 to $500 rent per week near Mortdale or Penshurst, Kogarah, Rockdale, and get more expensive as you move closer to the city.
In a big southerly, the water isn't too flat on Botany Bay either!
You'll might find living at Cronulla more fun though, more cafe culture, etc., the rest of the blue line is more quiet family suburbs.
Regards,
Harrow.