Muzna
Yes. Muzna (مزنة) appears in classical Arabic poetic and lexical sources as a term for a rain-bearing cloud; it has been used historically as a feminine name or poetic epithet.
Yes. Muzna is non-theophoric, rooted in natural imagery, and has been used in Muslim contexts without religious prohibition.
In Modern Standard Arabic it is pronounced roughly as /muz.na/, with stress on the first syllable: MUZ-nah.
No. Muzna is attested in classical poetry and lexica rather than as a Quranic proper name or term.
The lexeme is feminine in usage; related cloud/rain words exist in masculine forms in Arabic but Muzna itself is used as a feminine name.