Rumaysa
Yes. Rumaysa is historically attested in early Islamic biographical sources; Rumaysa bint Milhan (known as Umm Sulaym) is recorded among the Sahabiyyat.
No. Rumaysa does not appear as a proper name in the Qurʾān; its attestation comes from hadith and sīrah/biographical literature describing early Muslims.
Classical Arabic usage presents Rumaysa as conveying delicacy or a gentle/soft cheeked quality; the sense is lexical rather than a derivation from a frequently attested verbal root used as a common noun.
Yes. It is historically authentic, has positive connotations of gentleness, and is used occasionally by families who prefer rare, classical names connected to the Companions.
The best-known is Rumaysa bint Milhan, an early convert and Companion of the Prophet Muhammad, often cited in biographical collections under her kunyah Umm Sulaym.