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 a woman`s neck an Awrah (private part)?
All Perfect Praise is due to The Lord of The Worlds.
It is an Awrah, and it is forbidden for her to reveal it before non-Mahrams (Marriageable men). And Allah Knows Best.
Is it permissible for a woman to apply Kuhul (Halal eyeliner) and go out wearing it?
Kuhul is part of a woman`s adornment, and it is forbidden for her to show that to anyone other than a husband, or a Mahram (Unmarriageable kin).
I`m a building contractor. I have been building a house for a client, but the construction process stopped for some reason. Unfortunately, currently, prices of materials have multiplied, is it allowed for me to demand an increase in the agreed price?
All perfect 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.
It is more appropriate to approach the client and try to reach a mutually satisfactory solution. And Allah The Almighty Knows Best.