I'm not sure exactly how long the batteries would last before running out, but I estimate ~20 minutes in the illuminated state before being fully depleted. As for the soundboard, I used a Pico Crumble 2.5 Dark Edition.
I'm not sure who made this particular camera flash. It was in terrible condition when it arrived and any markings that were on it have been almost entirely scratched off over the years.
Thank you! This was my first build, and I'm very proud of how it turned out.