Impurity on body, clothes or place of Salaah

Q: At the ground where one places his feets during qiyaam, there is less than a dirham najasah and one notices this after salaah? Is the prayer valid?

Q: If someone sees the imaam after he has led the salaah wearing slippers with pigskin leather inside-soles. Did the pigskin leather inside-soles make the socks he was wearing impure? The salaah he led was it valid or invalid for everyone?

Q: Yesterday, when I went to toilet, I found stains of pre-cum (mazi) [I have this problem that often it comes out unintentionally). The stain was very small, probably smaller than a drop of water. Nevertheless, as I was in a hurry to join the Asr Salah in jamah, I forgot to change my underwear and even forgot to wash the stain. In this condition I prayer the Asr, Mugrib, Esha and todays Fajr Salah before recalling the incident. Now my question is should I repeat the four Salah prayed in the above mentioned condition or was my Salah valid. Can you also advise me on what to do for the problem of the mazi coming out.

Q: Is it permissible for the female Muslim to be perfumed (be'd with alcohol or not) or to have lipstick while performing namaz and reciting quran?

Q: A person who has prayed for a long time with a wallet made of pig leather (he was unaware of it). Does he need to repeat all his prayers he prayed with that wallet?