Some videos also on our group's YouTube page, with a quick walk-through. We already have one of these restored and open to the public, and we were after parts and a bit of exploration.
As for the accuracy, WW2 guns were good enough. This Youtube video on mechanical fire-control computers is very interesting and I've seen it come up on HN before several times. https://www.youtube.com/watch?v=s1i-dnAH9Y4
Lots of this equipment survives today. It was built to last and many people still collect it. We've also got about a dozen French and German cannon dumped from cliffs that we'll recover some day.