Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.
Is a woman`s voice 'Awrah even when praising the Prophet (PBUH) via satellite channels?
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.
The Sharia term 'Awrah has two meanings:-
First: `Awrah that invalidates prayer when uncovered, and in this sense a woman`s voice isn`t considered `awrah. Second: `Awrah that causes men to be tempted by women and vice versa. Moreover, if a woman`s voice is soft or alluring, then it is forbidden for her to speak deliberately before strange men. This is because Almighty Allah Says (What means): "O ye wives of the Prophet! Ye are not like any other women. If ye keep your duty (to Allah), then be not soft of speech, lest he in whose heart is a disease aspire (to you), but utter customary speech." [Al-Ahzab/32]. However, a man should avoid listening whatever incites his desires. And Allah The Almighty Knows Best.
Is it permissible to listen to chants praising the Prophet if accompanied by musical instruments?
If singing, or chanting in praise of the Prophet was accompanied by a forbidden musical instrument, then it is forbidden.
Is it permissible for a woman to visit the doctor while in her `Iddah (waiting period)?
It is permissible for her to do that during day time, but it is impermissible for her to leave her house at night except for a sound reason. And Allah Knows Best.