As with the previous dubs, I want to recreate Nepgear's voice as closely to the original voice actress as possible. As the VA, you'll need to be able to portray a variety of emotions in character, interpret and mimic tone based on the original Japanese clip, and have a decent understanding of the character in general.

Regarding the audition lines, the second one starts with Nepgear drinking coffee, hence the strange onomatopoeia.  It's basically the sound of drinking some coffee, then breathing out a sigh of contentment, like when you drink a great tasting drink and want to be over-dramatic about how it tastes.

Regarding voice references, I have the following two:
https://www.youtube.com/watch?v=1u0fbL70qiI This is a short collection of voice lines from the latest mainline game, Megadimension Neptunia VII.
https://youtu.be/oREypZEoxMY?t=52 This is a collection of clips of Nepgear in the Hyperdimension Neptunia anime. It's quite long, but it provides a decent overview of Nepgear as a character, and how she speaks.