I'm not sure how old these wall murals are; possibly late middle ages (I imagine that the knight is a Crusader), maybe early renaissance, but sadly they're showing some signs of wear.
I'm not sure what the font is; it's not the baptismal font which is larger, grander and of red marble. Unfortunately I don't have a shot of it, which surprises me. I thought I had taken more shots inside the Duomo.