1. Yumna means one who is lucky and blessed. We are unaware of any Sahabiyaat by that name.
2. Seeing the face and hands of a women one intends marrying is permissible. Talking is not permissible. If there is a need to ask any questions, it could be done via the females eg. the boys mother could ask the girl etc.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai