Hey,

Looking at the yact size first, it really depends on what you want to do. Something like an S97 is a nice size for the river, can race offshore and easy to drop the mast and cruise to Rotto with the Mrs.
The problem with a boat like an S97 is that they are raced pretty hard and well so you might get disheartened being beaten by a long way by the seasoned S97 crews.
With the older designs you have listed they are going to a bit cheaper for their size but they will have alot less room than a newer design and those masthead boats have pretty big headsails so alot of winching.
On the larger end of the scale, I have always been a fan of these http://www.boatsonline.com.au/boats-for-sale/used/sailing-boats/farr-1104/107606
On the smaller and racier end www.boatsonline.com.au/boats-for-sale/used/sailing-boats/mount-gay-30/86884

As far as clubs, when I left Perth 8 months ago pens were pretty hard to come by but that may be changing. South of Perth YC are a club that has plenty of pens and usually give preference to yachts that get raced often. They also have nice fleets racing.
My fav club is East Freo but getting a pen there can be difficult but if you wanted somewhere to go sailing on someone else's boat while you a learning and looking the guys there are hard to beat.

Either way I would recommend getting out there and doing as much sailing as you can before you buy. The winter and Valmadre series at Fremantle Sailing Club is coming up soon and is a great series to get out on the ocean and always guys looking for crew at both ends of the fleet.

Hope that helps

S80 are a great boat. Sailed one for nearly 10 years. They handle really well compared to other boats of that size. You need 4-5 people to race them hard but we could get very good results with just 2 of us as long as it didnt get over 15 knots.

Farr 40 are a whole nother level of sailing. They are fast and built for power. To race these hard you need at least 6 people on board that know what they are doing. Price wise you wont get much change from 150k for one thats in good condition. S80 should only cost you around 30k for a top boat. In saying that though you can buy not so good ones for under 20k.

Crew is always a big issue with boats. Its a hard thing but when at a club you will always find that those that can really sail will already be on a boat as regular crew. It can be really worth getting into some of the dinghy sailors ears to see who want to come play with the big boys.

River racing S80 - cheap and very lively.
Ocean going I'd want a bit more weight for a comfortable ride, best bang for buck there would be the UFO 34 I reckon.