MartinMA140S Authentic Acoustic - Marquis Silked - 80/20 Bronze Light (12-54)

Is there any difference in sound between this ma130s and the ma130 that isn't silk wrapped? anyone?

are these nickel plated?

are compatible with a martin backpacker?

Is this for a 12 strings guitar? Can I use this for a regular 6 strings guitar? Asking this, because the package says “12 strings”