Hopefully what I'm about to post ins't all crap. :)
1, they made them with both plastic and ally end tanks. Both should be good.
2, I'd think its AC, Intercooler then rad.
3, Yes it should cope with Stage 2/2+
4, The next up from the S3 I think are the APR/THS units.
5, It should do as they are all based on the same measurements.
6, Might need to replace/swap the pipes going to it.
Fish (waiting to be shot to bits)