A: Well, we would have said we have no idea, but we have had people in the UK deliberately order under a certain amount at a time so that the total does not hit a certain threshold that triggers customs fees.

But hey, we found this UK government page that looks really useful:
https://www.gov.uk/goods-sent-from-abroad/tax-and-duty

We’ve gotten the most complaints from UK customers, but other countries have duties too, so, if you’re worried about it, check around for info from your local government.