Muʾayyad
Yes. Muʾayyad is Arabic in origin, derived from the verb أَيَّدَ meaning 'to support' and formed as an active participle.
No. Muʾayyad is not a proper name occurring in the Quranic text; it is an Arabic participial form used historically as an honorific or laqab.
Yes. The name and its laqab form have been used in non-Arab Muslim societies historically, especially in scholarly and formal contexts.
Muʾayyad is an Arabic passive/causative participle pattern (mu- + verb-derived form) meaning one who is supported or reinforced.
It is suitable, especially for families seeking a dignified, classical Arabic name with a meaning of support and strength; it remains relatively uncommon today.