Amex is charged in USD I've found, even when the card itself is denominated in a different currency (GBP). EUR may be different, but I suspect not. So be prepared to eat a fee from Paypal on the currency exchange.

Paypal is a great example of how spammers and fraudsters have caused the company to shoot itself in the foot time and time again. They take natural steps to block users with different IP addresses, significant travel, or many cards. Unfortunately, this hurts the entry-level scammers and many, many serious travellers that actually need the service. This week I had two auctions bid on by Nigerian fraudsters which has caused needless hassle. Ebay's problems become Paypal's problems, but eBay doesn't want to stop these fraud bidders since constraints on bidding would hurt their growth numbers. Therefore they let lots of shady bidders on the site and eventually pass the hassles on to end users. I've vowed never to sell on ebay again after the hassles here in the UK, which seem even worse than in the US.