Aight lets not talk about tyres here as there are a few other threads RE that already. Lets try and keep this thread about springs/shocks/swaybars to reduce confusion.

As already stated, your best bang for buck would be to upgrade your rear swaybar as it will help you reduce bodyroll and understeer. Make sure you also get the heavy duty mounts to protect your subframe (see the whiteline site for more info).

Then you can do your springs/shocks.

Casor kit will help improve turn in at a sacrifice of slightly stiffer steering (which will in theory put more straing on your power steering system), but it should be fine.