Lovely site. Thank you! I grew small decorative gourds, spoon gourds, etc. with beautiful stripes. Are the colors preservable?

Yes, generally transplanting a plant is best done when it goes dormant. In the case of annuals or biennials it's usually not really worth the effort because annuals usually won't survive the cold season and biennials generally end up pretty ratty the second year if they're transplanted. It's always worth a shot with any plant though.

Wait until the flowers die back and then get enough soil to get a relatively intact root system. There's a good chance it won't be successful but as I said, give it a try. Foxgloves (and most annuals) usually replenish through seeding. Your best bet might be to get the dried seed heads at the end of the season and grow from scratch.