Just an update, for anyone in the future that might be looking at this old thread :)
-Got the full poly bushings installed, helped handling a bit but nothing amazing. Had them installed quite a few months ago and no noise issues so far, at least!
-Whiteline sway bar front and rear: not a huge improvement either, and looking back at it, I probably wouldn't have bought it if I knew. Front sway bar to the stiffest did improve turn in a bit but ended up being too stiff for the car, so switched it back to mid (rear set to softest) for a slightly improved turn in but not so stiff as to raise the front wheel off the ground in hard cornering. Installing the sway bars seems to have cause some clunking to now happen during hard braking and bumps.
-Rear strut brace made no difference as far as I could tell.
-Koni shock inserts: hard to tell the difference considering the stock shocks were shot before, but they do handle well, and the adjustability is an added bonus :)
-Waiting to receive a front strut brace, so we'll see if that does anything...
Previous owner said the springs were some sort of lowering springs, but found out that they are stock. I might look at upgrading them in the future (maybe).
The biggest handling improvement, by far, was going from 18" non staggered wheels to 16" 7" and 8" staggered setup.