To address a few remaining points:
While HMRC in the UK has been able to enact some concessions to ease the burden on UK merchants, those don't apply to sellers based elsewhere in the EU, and our VAT solution has to work for all EU sellers.
VAT on physical products remains subject to the VAT rate in the seller's country, rather than the buyer's place of supply. Products which have Shipping/Buyer's Address enabled will calculate VAT as physical goods at the seller's VAT rate. Since we now have to wait until after checkout to calculate VAT for digital products, as a practical matter we now have to calculate VAT for all products by the same method at the same time. Your Transaction Log will show separate VAT totals for each VAT rate applied to each order.
Our understanding is that EU sellers who have a VAT MOSS in their own country can just file EU-wide VAT returns with their domestic VAT MOSS, which would then redistribute any VAT due to other EU jurisdictions. Offhand, I'm not sure if EU sellers without a domestic VAT MOSS can file with another country's VAT MOSS; perhaps an EU merchant in this position can respond here to clarify.
It appears that non-EU sellers are now expected to collect and remit VAT on digital product sales to EU buyers, though we're frankly hard-pressed to fathom any actual consequences whatsoever that low-volume digital-goods sellers outside EU jurisdiction could possibly suffer for failure to comply. Non-EU sellers can comply by filing all their EU VAT returns with a VAT MOSS in just one EU country (e.g., the UK's VAT MOSS).
