you can still use gtst suspension. easiest way would be to unbolt the ankle/ knuckle on the gtr hub and bolt on your gtst one. but you do need to use the gtr hub as they have a different number spline.
yes you can use all gtst arms as long as you use the gtst ankle, u dont even need the gtr subframe.
the difference with the lower control arm is that the ball joint that mounts to the ankle is alot wider then the gtst one