Mu'in
Yes. Mu'in is an Arabic name with classical attestations and is used historically in honorific forms such as Mu'in al‑Din; it is permissible and historically used among Muslims.
In Arabic Mu'in (مَعِين) means 'helper' or 'supporter'. In Urdu it is rendered as مددگار، معاون.
Yes. The most prominent is Mu'in al‑Din Chishti (1141–1236), the South Asian Sufi saint; the name also appears in various medieval honorifics.
No specific proper-name occurrence of Mu'in appears as a personal name in the Quran; the root ع‑و‑ن (aid/help) appears conceptually but not as this proper name.
Pronounced /muˈʔiːn/ (moo-een). Variants include Muin, Moin, and the honorific compound Mu'in al‑Din.