The trains themselves were consructed by Adtranz / Bombardier and can run on third-rail and various catenary voltages, with a maximum design speed of 186 mph.
London to Paris takes 3 hours. London to Brussels 2 hours and 40 minutes.
As a whole the system is attractive compared to air travel.
The company that runs Eurostar is a joint venture between Belgian, French and British railway companies. On the train itself, French, Belgian and British currency are accepted, though this should probably change with the wider introduction of the euro.
The border between France and the UK is in the middle of the tunnel. On re-entering the UK, British IND (Immigration and Nationality Department) staff are usually seen on the train.