Yeah, what Walter said!
Apart from that, I agree that he wouldn't need traveller cheques. It's a hassle to cash them. Bringing a bit of cash for what he would need after getting to the airport, taking a cab or bus or train should be sufficient. Then again, there are ATMs at pretty much every airport, so he just could bring a card and would be fine. A Maestro (compatible) card is recommendable (see
here). Withdrawing money from an ATM with your credit card has usually a rather hefty fee attached to it.
Cash is generally more prevalent than in the States, and you might not be able to pay with a credit card in each and every place. Plus places that generally accept credit cards might refuse them for rather small amounts of money.
Shops are NOT open 24/7 ... something to keep in mind for planning your shopping tours. In smaller towns or cities, pretty much everything might be closed on weekends or at least on Sunday.
Many people speak English. Especially people in the bigger cities, younger people, people in the Scandinavian and Benelux countries, and some even in Ireland and Britatin. If he's planning to stay in youth hostels, he shouldn't have any problem at all.
Travelling by train is really a nice and easy way to see the place, and yes, those passes still exist and are now called
Eurail.