you can add more castor with whiteline's castor kit, which is pretty much a washer kit installed on the control arms to create the additional castor angle. Not a very elegent setup but it sure works well and only cost about $50 plus install.
hard to troubleshoot your problem in front of the keyboard without experiencing the suitation myself. I've driven plenty of ED, EG civics with over 200-300ks on the clock with the orig suspension ie shocks, bushes and the rest that are getting worn and yet the car still tracked true and felt stable to me. And since you have half decent tyres and looks like 15" wheels ( rotas? ) so the vagueness wont be from gripless skinny tyres either.
koni yellows great choice, make sure you install them front and rear with the set of dc2r springs.
Best to get a competent and honest suspension place to check out your fundamentals before installing your mods and speculating what could be worn or not. Wilkinson suspension or Glide are the best in Perth in my opinion. I got a wheel align done at a bob jane tyre shop out of convenience and while they adjusted the toe settings fine and gave it the ok, they failed to notice I had 1 neg of positive camber on one wheel caused by a damaged stub axle that was bent when I mounted a kerb once.
