Nashwan
Yes. Nashwan is an authenticated Arabic adjective (نشوان) found in classical lexica and poetic usage and is attested as a personal name in some Arabic-speaking communities.
Literally it denotes being in a state of joy, rapture or pleasurable intoxication—often used poetically to describe emotional exaltation.
No, there is no explicit occurrence of Nashwan as a named person in the Quran or canonical Hadith collections; its usage is literary and lexical.
Yes. Because it is a classical Arabic lexical item with positive connotations, it can be and has been adopted in various Muslim cultural contexts that value Arabic-derived names.
Traditionally Nashwan is used for boys; its grammatical form is masculine in Arabic usage.