Does kissing a non-mahram woman necessitate ghusl, and does the presence of discharge in the underwear necessitate ghusl?

The wetness that appears on clothes after caressing women is usually madhy (pre-seminal fluid), which nullifies ablution (wudu') and necessitates washing the male organ and purifying the clothes. Kissing a non-mahram woman is a sin that requires repentance and may lead to greater indecencies.