Like Matt5112 said, get all the rubber. Otherwise the springs will be metal on metal with the rest of the strut and will make noise. The insulators are cheap. Don't know about the top/rears insulators as I did the GR2 strut plus assemblies in the back. Maybe they are part of the rear mount.
Don't forget the bellows to shield the strut shafts from dirt. I think I had to order them separately. But since you have the GR2s already, you can check in the box.