Worshiping Nyx is not considered Witchcraft alone. You are simply worshiping Nyx. If you wish to practice witchcraft research it before aligning yourself with any deities (i.e. Gods/Goddesses). Witchcraft is not particularly a religion and therefore the worship of Gods and Goddesses is not a rule/must, but many Witches do honor their deities.
No. It is not a crime.
The name of the school in the series is 'Hogwarts School of Witchcraft and Wizardry'. Reading the books is not witchcraft, but it is a large part of the plot.
because men were considered to do wizardy and sorcery, not witchcraft.
Nyx
Yes. Nyx personifies Night.
Nyx's mother was Chaos. She had no father.
The name "Nyx" has no vowels in it and is often considered an Indian girl's name.
Nyx is the greek ngod of the night.
Erebus (Darkness) was the consort of Nyx (Night).
Nyx is the figure of night
One can purchase NYX eye shadow at their website, NYX Cosmetics. Nordstrom is a retailer of NYX cosmetics and sell eye shadow. There are a couple of eBay stores that sell NYX products including eye shadow.
Nyx was the deity personification of Night.