You will want to go straight to the gate for your second flight; no pottering in the duty free at AMS. You are supposed to be seated aboard your second flight 30 minutes after your first is scheduled to arrive. If your NCE-AMS flight is more than 30 minutes behind schedule you are in danger of not making the connection.

Your second flight is operated by Northwest Airlines with a KLM codeshare flight number and will probably depart from the E pier at AMS, which is centrally located. The B757 is a narrowbody with 3-3 configuration in economy, yes.