It has been debated for some time whether the S1 Pro is a 3mp or 6mp camera. But it doesn't matter. When I was using the S1 I found the photos looked better then what the Nikon D1 series cameras produced. The color was gorgeous. At native ISO the photos had a fine, very detailed look. I sold it maybe 10 years ago but to this day I'm still thinking about picking one up just to see if my memory of the photos still holds true.
As for your 35mm f2.8 S lens just be sure it has either the AI factory conversion or has been AI machined. That lens was made prior to Nikon's AI mount release.