Finally built my Circuit Gem VMU and it went pretty smooth but I have no audio. The speaker seems to be soldered correctly and I tried editing the Retropie audio settings. Any suggestions?

Is this one too big? https://www.adafruit.com/product/1578, it's a little bigger than a quarter.

I may omit the shoulder buttons on my curcuit gem VMU build since the Pi zero doesn't handle SNES really great but I was wondering if anyone else has left them out and if you regret it. But in case I do, what buttons do you like to use?

Is there a specific battery that someone can recommend to fit in the VMU for my Circuit Gem project?