Is there a wind deflector available for the A4?
If so, how much and source?

Can any suggest how I might find the part # for the chrome mirrors available on the European S4 and whether they are compatible with the auto dimming feature in the Convenience Package option here in Canada.

Stan '00 1.8Tqmx (on order)

you might do an archive search on the subject. Some people here have thought they weren't worth it and that they caused some damage, if I remember correctly.