Ill bite.
Southside. Try Kyeemagh on Botany Bay for fantastic blasting in NE sea breezes.
A bit further along try Brighton-le-Sands in southerly winds.
Kurnell further around in NE, N and NW.
La Perouse on the opposite side of the bay works in certain conditions as well.

Northside.
Pittwater at Palm Beach works in NE seabreezes and NW winds.
Further south at Sand Pt gets good in a southerly but gets quite big chop.
Narrabeen Lake works in most conditions but has become very shallow so some spots dont work anymore.
Try the western end in a NE seabreeze. It funnels in here and is usually 5-10 knots stronger than the beach.
North side (Bilarong reserve)works good in SE and W/SW winds, same deal, they funnel in.
As for hiring, just see Sam and Chris at Wind Surf n Snow on Anzac Ave at Collaroy, they will sort you at.
Cheers.