I need your help with some suspension issues please

[MAXIMUS Nismo]

The car is a 95 Zenki with a about 160XXX miles.
Suspension currently consist of KYB AGX and eibach pro-kit all round installed Dec of 2004.
Bushings are all original.

Here's what's going on. The settings on the AGXs are usually F2 R4. I used to keep it at F3 R6 but I hurt my back and can't drive for long at those settings anymore.
1st Question
With the age of the car, how do I refresh the handling without making the ride harsher? I was looking into replacing the anti-sway bar bushings with polyurethane and the other suspension bushing with OEM rubber. Please advise.

2nd Question
This is the more serious issue for me. If I go over a line in the road at speed, like a raised expansion joint, especially if it's around a corner, the hops left or right.
Let me try and explain. For those of you who live in MD and drive around the 495W to 95N area, College park side of the beltway;
When you take that right hand corner from 495 to 95N, the rear of the car will hop to the left while in mid corner when I hit that bump that stretches across the lane.

It's very scary and disconcerting. It even happens if I'm driving in a straight line but not very pronounced. I know it's there because of my knowledge of how the car feels.This issue was barely and I mean barely noticeable when the AGX and prokits were first installed.

I hope someone can help.
Thanks in advance.

[LoserCard]

I think what you might be experiencing is a blown strut(s). When a strut blows it doesn't provide the dampening that is supposed to and literally causes the wheel to bounce a couple times quickly (as opposed to once slowly) when going over bumps. This in turn causes a loss of traction for multiple instances (bumps), and when it comes to traction you want your tires to be in contact with the ground as much as possible, especially during a turn.

***OR***

Your bushing are going out which will cause a bad bump steering problem because the suspension arms are not moving in the correct directions. It is almost like turning slightly when ever you hit a bump.

In any case, just replace all of them and call it a day.