The conversation with Nel about men has no continuation in either the stable version or the current beta version. So it's a dead end for now.
The new hairstyle is sort of an easter egg, but basically, to unlock it, you need Nel to become the full owner of Celica's body and she starts changing it. To do this, you need to reach 5 points in the body control scale, using Kimiko's shrine magic and Nel's activity. If this is achieved, then you need Celica to come to her house in the body of a Puppet or an elf. This is the only easter egg we are discussing here.
About clothes. Maybe you should share more of what Celica has with the crew. Especially with the girl who is the captain's first mate.