They are passing "prefix", "ending", and "extraNames" in an object. It's just defined inline in the function and using destructuring so the function can access the keys by name without having to put the object in a variable (and the default values are part of the object destructuring).

The model is dragging the head itself as if it is a joystick. Left and right don't swap, but arrow up maps to forward, which tilts the head down.

Put your finger on top of the character's head. Left and right are still left and right, but forward (up on the controls because of how they're positioned) makes the character look down and backward makes the character look up.

When I was a kid, all the controls by default were what is now called "inverted Y-axis" and rarely had an option to change it. I think it flipped around the 2010s, I remember being confused when I bought my Switch and got back into gaming.

> as it zooms around the character's head.

This is a third-person camera. First-person is strictly seeing from the character's eyes.