i wouldnt be using the xt strut in the wagon. you will get a lot of camber.
for corona, use ra60 celica (or stock if theyre the same) struts and nissan 4 pistons, the 4 pistons calipers bolt up to the celica struts. discs.. dunno. toymods has the answers though.
only pics i have, can see the spacers in the top pic.
re the sumitomo calipers, i think the problem is you cant get many pads for them.