Thanks so much for taking the time to put this whole post together, zmove.

I'll chew on this for a while and we'll see where to go next. I'm sure we can put this all into one module that's usable for Ubercart 1.0 and then work it into core for 2.0. We'd be happy to have you on as a co-maintainer/adviser.

I may look into that osC contrib to figure out how they're validating VAT numbers, too.