Scuderia Vittoria Edition 001
looks very nice! In answer to your questions;
You can modify your original exhaust to fit, depending on how competant you are/feel though you may want to take it to a garage for this.
I believe OE s3 door blades will not fit a3's as the dont have the runners.
The clocks can be swapped across but will need to be coded to the ecu and key
The s3 springs were a higher spring rate iirc but the shocks dont fit because of the arb at the front and the way the shock is mounted on the rear.
Hope this helps and im sure people in the know will be along to correct me and answer your other questions
''If a hammer doesn't fit it. it's technical''
AH Fabrications catch can for sale £50 posted!