Btw ALEX operate the 9:04 and 17:04 departures, any other trains wont have the option to buy the ticket on-board that cheaply.

Its a German/British train not a Czech one. Its hard to say, I guess they're very new trains but nothing fancy at all. First class probablly has a little bit more room, classier accents like wood tables or something on par with tat. It seems like they don't even try to sell seat reservations so I doubt that the train is normally full, I guess second class is comfortable.