According to this teardown, the iPod Nano has a chip labeled: Apple 33850859. Is this the D/A conversion chip? Does it handle audio output?

According to the iPod touch 4th generation teardown: "On the far left is a 338S0859 chip. It's similar to the Cirrus Logic audio codec of the iPhone 4 (338S0589)."

Are these two chips (Nano and touch) identical even though one seems to have an S instead of a 5?

Which one of these chips handles the D/A conversion and audio output? I'd like to know so that I might compare it to the iPod Nano and touch.

Sorry if I'm missing something here, but what is that secured to the rear panel (visible in step four)? I see four screws holding the clip onto the rear panel, but there doesn't seem to be any teardown of that segment of the Shuffle.