Actually, there are a couple wifi channels that are inaccessible on a US wifi card (due to FCC regulations.)
But, most wifi should work fine on a US card elsewhere. (And, if it's a problem, most wifi cards will let you flash them to European firmware.)
Power won't be a problem, every laptop I've used since the 1990s has had autoranging power adapters.
Also, buying a business machine is a good idea, with the premium warranties that come with them. Those warranties are usually international, so you can use them anywhere, not just the country where you purchased the machine.