I think you will be on a Airbus 300. A kinda old plane, basic entertainment system, blah cabin. The "business class" - Club Europa(?) is 2x2x2, maybe 18 or 24 seats total. Pretty good legroom. The food is pretty good and the flight crew I had was very nice and there seemed to be alot of them. Overall Czech business class is inferior to Delta Business Elite or US Airways Envoy or Continental Business First (IMO), might be better than Northwest.
You should have lounge access in JFK, the airport in Prague has just one VIP lounge for all airlines.
Prague is incredible - have a great trip.