caster rod bush? it may cracked... get a replacement kit from whiteline.
for brakes, call RaceBrakes in north melbourne, they will recommend something suitable for you.
replacing your shocks, the price will vary depending what your expectations are on performance and features. I'd say go for coilovers (damper adjustable, height adjustable, pillow ball, etc.). But you could also select high end shocks and springs seperately to suit your requirements.
Ohlins == very good sh1t.
GAB shocks, kg/mm springs == good sh1t.
Nismo, HKS, TEIN == ok as far as coilovers go.
Hope this helps. Cheers B)