The Bay is a real beast ....
At last we have some chop-eaters available, designed especially for Port Phillip - Martin Love's new board
www.atomicwindsurf.com/masterblaster - or the Severne Fox - or my personal favourite the Windtech Silver Bullet, for your needs maybe go the 72 but the 64 would also be fine
On sails, so many great options - probably a 7m, up to 2 cams - for me at 90kg I would be comfortable on 8.6 in those conditions
Hope that helps