Wahshi
Yes. Wahshi ibn Harb is a documented figure in early Islamic historical sources and biographical literature; he is known for actions during the era of the Prophet Muhammad and later conversion.
No. The name Wahshi does not appear as a proper noun in the Qur'an; references come from sira (biographies) and hadith-related historical accounts.
Wahshi literally means 'wild' in Arabic; while historically attested, many modern families avoid names with harsh literal senses, though some accept it for its historical link.
The word is Arabic in origin; the most famous bearer, Wahshi ibn Harb, was an Abyssinian who appears in early Islamic Arab historiography.
There are no widely established diminutives in classical sources; modern variants may attempt phonetic softening, but the historical form Wahshi (وَهْشِي) is primary.