What is the ruling on feeling a movement in the anus; does it nullify Wudu' or not? And is it of the same nature as wind or not? And is it permissible in Takbirat al-Ihram to raise the hands before the Takbir, or to say the Takbir before raising them, or both together?

The fundamental principle is that ritual purity (tahara) remains. So, whoever feels a movement in the anus but is not certain that gas has been emitted, their ablution (wudu') remains valid, and their prayer is sound. Raising the hands during the opening takbir (takbirat al-ihram) is a Sunnah. The preferred way is for the raising to begin with the start of the takbir and end with its conclusion. It is permissible to raise the hands before or after the takbir, though some scholars consider it disliked (makruh).