quattroworld

Ignition switches are an issue in the B4s (not sure why they are not in the Coupes, I've had 3 and never a switch issue). It's worth checking for sure, you just need to unscrew the trim over the column (2 phillips from below), then remove the binnacle (2 phillips covered by the trim), remove the harness from the binnacle, then you can see the ign switch which is secured by 2 small flathead set screws. From the factory these set screws were marked with red paint, if yours still has the paint intact I would replace it regardless of the issue. They are fairly cheap, NAPA should carry one, lots of opinions about what brand of replacement is best but any shoudl be better than a broken one.

WRT the regulator, you'll need to get those isolators from a recycler Audi does not sell them without the regulator. Joe Marconi, audicoupeparts@yahoo.com, probably has them. Also, I think somebody found an isolator from McMaster Carr which is close.

TlDr, STFA & Search 12v.org ;-)