Well, yes and no and yes.

KLM (and all NW gates in Europe are staffed by KLM) does not offer elite checking and preboarding to Silvers (even their own) at all locations, so you need to pay attention to the signage. For example, at FCO the first-class checkin is offerred to "Skyteam Elite" which includes silvers, but when I passed thru CDG on May 1 it was limited to Golds & Plats.

At the gates for the transatlantic flights from AMS, the checkin is a two-stage process. First you get in a line for the stupid security questions. The WBC line is usually short/empty & roped off but I know they will let Golds & Plats thru it -- I just walked up to the WBC line for our return flight at the end of July & asked if a gold could use it, they smiled & said sure so my wife (SE) and I (GE then) managed to breeze thru that checkpoint. I'd suggest you have your Medallion card handy & try it. The second step is is where they scan boarding passes. Here there is usually an elite line to left of the normal line, just watch the signage. Unfortunately, when they call for elites to actually get on the plane, there never seems to be anyone checking boarding passes on the ramp, so they might as well just say "y'all board now".

KLM departures from the US are handled by NW where NW also has international departures, and by outsourced gate agents in places like ORD & the E concourse at ATL. My limted experience (ORD-AMS) is that they follow the NW way of doing things in the U.S. I wasn't elite when I flew ATL-AMS so I really didn't notice.