Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.
My headcloth is causing me a terrible headache and severe shortsightedness. Is it permissible for me to take it off?
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
If the headcloth Khimar is harmful, it is sufficient to wear the Niqab (face-veil). However, with the passage of time you will get used to the Khimar and these symptoms will go away. And Allah The Almighty Knows Best.
If the imam does not leave time for reciting Surah Al-Fatihah, is the recitation of Al-Fatihah waived for the follower?
The recitation of Al-Fatihah is not waived for the follower. They should recite it silently, even if it causes a slight delay in following the imam in bowing (Ruku'). And Allah Knows Best.
What is the ruling of Sharia on exfoliating the skin on the face?
Praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
According to medical doctors, exfoliation means removing a layer of skin to expose new skin. If this procedure is harmless then it is permissible since this is a kind of treatment and not skinning. And Allah The Almighty Knows Best.