There are a lot of things that can cause understeer. I use a chart like this, I have adjustable sway bars, at the track when I am dialing it in.
It helps when your tires are the same brand at all four corners.
I do think bushings before coilovers because you need a solid foundation to build on. Otherwise you will not get the full benefit of the coilovers. If you have someone near you that has bushings try and hitch a ride to see the difference. Night and day.