Yes, it's a black suit, which means skip the navy. Navy and black don't really play well together.
I would go with charcoal on that one. I wouldn't do black during the day, just too harsh a contrast with the black suit as well. A black knit or grenadine would be great for evening or night though.
Negative, it actually isn't black. In the picture it does look very black but its actually a shade of blue. I've attached a photo compared to grey pants. Must be the lighting.